look at something like this:
https://sfbay.craigslist.org/sfc/boa/4462076344.html
thats a couple months rent for more people here in sf. once you buy the boat is it nearly costless living? what other expenses are there? ive heard people say before to NEVER buy a boat
Costless living on a boat? HAHAHAHAHAHAAAAA!!!
Now. let me preface this by saying I'd really consider living on a boat, even married with 3 dogs and 2 cats. But it'd have to be the right boat, which this isn't.
First, while the slip for the boat is "included", all that means is the new owner can continue the rental of the slip the vessel currently inhabits, not that the slip is included in the price. Treasure Island Marina has a waiting list for slips, esp. liveaboard situations.
The BASIC cost of the slip for a 35' vessel is currently $357/mo. This does not include shore power (you're going to need elec. power and relying on your own generator is incredibly expensive). The current charge per their website is $3.50/mo connection and 14.2 cents/kwh. Not too bad, I guess.
But that's only the start.
You're going to have to have the vessel pulled from the water at least every other year for bottom cleaning/scraping and anti-foul painting. Not cheap. And given you're in salt water, probably a yearly expense.
Then you have to pay critical attention to the very real probability of galvanic corrosion on any exposed metals in the water, like the outdrive of the diesel engine. Again, not horribly expensive unless you don't keep up with it.
And then you're going to be spending a LOT of time cleaning, and cleaning, and cleaning everything on that boat. Sitting in salt water, surrounded by salt laden air, tends to corrode anything and everything. Remember, this isn't a well sealed house but a drafty, poorly sealed boat. Every inch of that boat, both interior and exterior, will be subjected to salt air and that will attack every inch of the boat. Priced a new main sail lately?
You can keep up with it, but it's a lot of work.
And also remember, you'll be living like a hamster. You'll have a fridge that'll hold 2 days of fresh food. You'll have a head (bathroom) that will have to be pumped out every few days. Your shower.....while it'll have one as a matter of fact, it'll be more of a suggestion of a shower in use---very small at best.
And those are the highlights. Remember, there's going to be insurance costs and they're going to be much higher than a "regular" house's insurance costs. And maintenance on the engine and generator. And on and on and on..........
You can do it, but cost free? Not a chance in hell.