My home button was completely unresponsive, so I bought a cheap one of eBay and replaced it. The fit wasn't right, and after a few days, the button was stuck in the down position, making the phone unusable. It seems like the button was too thick, as the glass pushed it down and activated it.
Both times, I used the guide on iFixit and the repair went perfectly. The second (quality) part from iFixit was flawless and functions perfectly. Well worth the extra money to get something that actually works.
Don't cheap out on parts for your phone. Your time and frustration dealing with shoddy parts isn't worth the money you'll save.