You might want to hit a few pawnshops in your area, as you can probably find a good deal on a used 500 or 870. I am partial to the 500, simply because that is what I have...
Once you have either one, you can purchase folding stocks, or black plastic fixed stocks, pistol grips, extended mag tubes, and many other accessories for either one. It just depends on what you want to do with it, though most of the accessories will be very easy to swap around, so keep it in home defense dress 90+ percent of the time and the other times you are trap shooting, just put the wood outfit and long barrel back on. Price wise, $280 doesn't seem like too bad of a price with the both barrels, but I haven't priced them in a long time, as my 500 was a given too me by my ex-girlfriends family, as they inherited it, but were not enthralled by the thought of having it.