Generally, unless you are buying in bulk you are going to struggle to make money on ebay/amazon selling video games...
If you are looking to sell retail and at market stalls ect then there is money to be made.
For a new release title you are looking at around £26-£27 (PC & PS2) trade price from most of the main wholesalers. I know this because I was in the DVD market for many years and thought about going into video games only to find that there was less margin to be made than dvds.. :eek:
With regard to finding wholesalers I have a few contacts but the price of £26-£27 a title is fairly complimentary until you are buying 1000's per week of a title.
Hope this helps as a starter,
Anthony