Rythmik makes good subs. The lowest I've gone on their food chain is the F15, but I would expect the entry level models to sound and operate similarly, just with less output. The guys at Rythmik are very approachable. I'd reach out to them and get their advice. I like Rythmik a lot, but you might also consider SVS and Power Sound Audio.
I am an advocate for multiple subs, and if you go that route, the entry level models will work great. If you're only going to get one or two, you probably want to save up and get something with more output for that space.
It doesn't matter if you rent or own your home. If you "own" a condo, putting a bunch of subs in it may not be the best idea. If you rent a house and it's well insulated, not 3 feet away from your next door neighbor's house, and you don't play everything at top volume at all hours of the night, you should be fine. Exercise common sense and don't get put off by some of the condescending posts.