I did my own install. You can definitely pay someone to do it as well. It's not cheap though.
It took me a good three solid days to setup 8 glass breaks, 2 fire sensors, a couple alarm panels, the cellular uplink, the ip communicator, two lock boxes, 20 or so wireless sensors, two sirens, three motion detectors and the wireless transmitter.
I also had to wire in the X31J (maybe the wrong name) for line interception.
A tech is going to probably want at least $50 per hour...
ADT and the like only throw in a couple wireless sensors, a motion and an all in one keypad/siren/brain module. Plus you are on the hook for $30/month in monitoring.
My system was about $1600 I think and a lot was extras/overkill.
Security systems are worthless. If the thugs cut your phone line, wear ear plugs, or just don't give a shit, or if the police take 2 hours to respond to an alarm while your house is cleared out, none of the security companies are going to pay to replace your stuff. Someone who wants you dead isn't going to care either. You're basically paying for nothing or what I like to call negative-insurance. Like others have said, get a sign and some stickers and make sure your insurance is up to date.
Your system was definitely overkill, I know banks that don't have that much security. But since you did it yourself it was not terribly expensive overkill (most of the items on his list are the expensive up sells that companies use to really get you for, I would have charged you more like 5k for all that, but my techs would have had it up and running in a few hours instead of days.)
First my philosophy: There are basically two types of robberies, smash and grabs, and looters. There is not a lot that can be done to stop an accomplished smash and grab. They break a window, grab a high value item next to the window and are gone in under a minute; the window sticker is as effective as the alarm against this sort of criminal. If they think you have an alarm they are more likely to check your neighbors out instead.
The looters are the teams of crooks that clean out a house, or rummage though the house for valuables. They are what alarms are highly effective aginst.
Besides stopping thieves there are two other uses for an alarm, fire alert and access control.
Everyone should put fire alarms on their alarm systems, it is highly effective and the savings on your insurance will pay for it in short order. Access control is a more advanced use, which I will talk about in a bit.
So, knowing that here is what I recommend for most houses:
Fire Sensor: preferably a heat change sensor, situated near the kitchen or hot water heater. Most houses can get away with one of these, but this is one item I would consider adding more of, especially if the kitchen and hot water heater are not near each other. This is something alarm sellsmans are trained to try to up-sell you on, instead consider the next item.
Several non-monitored smoke alarms in or near each of the bedrooms. These things are cheap and effective at saving lives in an emergency, and you don't need a company to install them. Everyone should know to have these by now! A monitored fire alarm is NOT a replacement! If you have a fire sensor in the kitchen and a fire starts in the master bath while you sleep you will be dead the kitchen alarm goes off.
Control Panel(s): One of the most expensive parts of a system, it has the main guts of the alarm in it (yes, you can buy access panels and control panels seperatly, but unless you are buying in bulk it is probably not worth it.) Go with just one of these near the door the house mainly uses, but I consider it a reasonable up-sell to add a simple (and cheaper) add-on panel in the master bedroom. Just be sure to set a long delay between activating and arming of the system, I will often go with the maximum the system will allow, normally 15 minutes, because it greatly reduces false alarms by giving you time to set the alarm at the main panel by the garage door and still go back for the jacket your forgot, and leave though the front door.
Motion sensors: Most important part of the system IMHO. Most people use these wrong. Dont set them up to look for people, set them to look for doors opening. I put one in any hallways that have bedrooms/offices off of it. I set the sensitivity low enough to that it is not set off by even large dogs, but will catch the doors moving, sometimes by only watching the top third of the door. If there is a media room or other room that has high value items (my computer room for example) I will put one looking over that room. Each motion is on its own zone, allowing me to control access to parts of the house while allowing people to move in other parts. For example, I can turn on all the downstairs zones, effectively stopping access to the house, while kids can still get up to go to the restroom. There is all sorts of things that can be done with this concept, for example you can set the system to beep the master bedroom panel anytime the zone that watches the kids doors are opened with out setting off the alarm.
Contact Sensors: These are what I use to flush out my system. They go on main entry doors, and any windows that I want to monitor. I dont normally monitor windows because it is not all that useful, but Ive found a lot of parents like to monitor kids windows. I dont find monitoring windows useful because smash and grabbers are gone too quick for it to matter, while looters will move deeper into the house and set off a motion sensor.
Backup battery: Get a good battery. Find out what your panel recommends, and get it. Dont cheap out here.
Siren: Get two sirens, an indoor siren should be loud but not deafening, and an outside siren that should wake the neighbors.
Flood Lights: I think that the motion controlled flood lights you see in so many neighborhoods are useless. But a pair of powerful floodlights that come on with the alarm goes off is one of the most powerful tools you can have. Get two of them, one in front and one in back.
Window Break Sensors: Another thing I dont use. They are IMHO useless. An alarm is not meant to keep you getting your windows broken, it is meant to stop you from getting robbed. It is too expensive to try to monitor every window. It increases the costs dramatically as you need a more expensive panel and all the sensors, and if you are doing a wired system (which is what we did) it costs lots of time to have all that installed. With all that, Ive found that they are simply not that effective. Ive seen lots of broken windows that had sensors that never went off, and even more false alarms where a sensor went bad or got damaged. (Ill admit that this might have changed, we decided to stop even offering them years before I quit, and Ive been completely out of the business for the last 3 years, so my info on these are about 5-7 years old)
Cellular/Radio/other comm backup systems are useless in my opinion. 10 years of running 2 alarm companies and I can honestly say that in hundreds of thousands of alarms I have never once seen a burglar cut a residential phone line prior to breaking in. Even if they did, most monitored alarms have a wire cut detection system that sends an alarm off if the phone line is cut. GSM backup is almost completely wasted money, the companies love talking about it because it is one of the most profitable up-sells, but it doesnt really happen.
If you have any questions, I'll be happy to answer.