It has probably been going up since more and more people are getting into moding their vehicles. I do it cause it is a hobby for me and I love cars personally. Keeps me out of trouble, until I take her on the road and get on it.
I think overall e-bay is a good place to get a lot of stuff, you just have to make sure you are getting a good product and check up on who is selling it and some other things. But for the most part e-bay is a very nice setup to buy and sell things. I only know one situation that my friend bought a computer on ebay and sent them a check and they never sent him the computer. It was for like $1200 too! Just be careful is all you can do.