I live on the third floor of an apartment with one Yorkie and one Whippet. They are both outdoor-trained. It's not too much of a hassle to take them out several times per day. I live with my younger brother, so someone is usually around to make sure they get plenty of chances to take them out throughout the day.
Our apartment required a $400 total non-refundable fee. $300 for the first pet, and $100 for the second. I hate that it's non-refundable because my boys don't do anything damaging, but oh well.