I've used them for appliance parts and small engine parts, they're fair just make sure they have it in stock before you buy and find out if it's an OEM part or an offshore manufacturer.
I had to buy new spindles for my mower deck and the offshore ones I got didn't last the season, the castings were full of voids and I had to replace all three twice, initially I saved about $20 on the ones from replacementparts dot com but in the end I spent the money and bought the OEMs and have had 2 seasons no problems.
As far as appliance parts go, I've had no issues and they have a excellent interactive program to help you identify parts and what they actually look like.