Buying parts on eBay

Hit and miss.

Buy 1 before buying 10. Test it.
Buy 10 before buying 100, Test 'em. e.t.c.

Sometime the parts are marked nicely with fakes inside, sometime they do the opposite thing :)eek:)

The same seller may sell you genuine parts along with fakes :)

Your safe bet is to go digikey et al.
I have found that the time and effort involved along with shipping charges for buying small parts from eBay makes it worthwhile only if they are passive parts you can't easily find anywhere else - otherwise use Digikey. With active parts you really don't know what you are getting from ebay, just too many bad stories of fakes - for the sake of a few $ compared with all the time and effort you will put into your project just buy from a reputable source.