A while back I had thought about getting a concept 2 rower to do this. It's a high quality piece, can be stored with minimal space, and is pretty economical compared to high quality treadmills, ellipticals, etc. My gym has one and I use it from time to time (it can take a little work to get the form down properly.)
I also considered a water rower. There are various pros and cons. The water rower is supposed to be quieter which would probably be helpful if you wanted to use it while watching TV. I've never used one though.
Ultimately though I didn't buy either. My new development has a fitness center with TV and some cardio pieces so I just go there. It's probably better-- I don't really like working out at home anyway.