Drums in an apartment isn't just a noise concern... it's probably also a space concern. I've got a Roland HD-1 for my apartment and while it isn't perfect, it works great for me in terms of having a small footprint and allowing me silent practice.
Things to think about when looking for an electronic set in an apartment:
- The biggest source of noise with an electronic drum set is the 'clacking' of hitting rubber pads with drumsticks. If you can afford getting a drum kit with all mesh heads (as opposed to rubber pads), do it.
- The next biggest source of noise (and vibration) would be hitting the kick drum trigger with your pedal. The Roland HD-1 has a different mechanism which eliminates this vibration, but the mechanics aren't quite the same as an actual kick drum (pretty close, but might feel weird if you're just starting out). I've seen people build drum risers out of plywood and tennis balls... it sounds a bit weird, but apparently it will pretty much eliminate any vibrations travelling through the floor into someone else's unit!
- Almost all of Roland's kits (with the exception of the HD-1) are upgradeable. This means you could buy a cheap, used kit with rubber pads and then upgrade them over the years through individual pad purchases. Roland equipment is surprisingly robust, so you're usually in good hands buying used.
- Make sure you try it out in-store before bringing it home (especially the HD-1)! An electronic kit, while great for practice, is still different than having a full-on acoustic kit. It will feel a bit weird at first, so make sure you know what you're getting into before you spend a lot of money!
Finally, a good forum I've used for electronic drum info is
www.vdrums.com. They have a Roland slant, but for the most part the posters on there are very knowledgable and willing to help out!
Good luck!