I only trust amazon so far because they are the only merchant on this website I have bought something from before. However, their prices are too high compared to others. Can I trust the other merchants?
They would not be on this site if they were not trustworthy :)
I have heard a few horror stories from places like eBay, so I just wanted to be sure.
If they are on this website they are vetted.
Ebay, parts are mostly sold by individual people or small companies so make sure that the account is reliable and has a good rep before you buy from them. If something is to good to be true, it usually is.