I've been on a bit of a spending spree lately, and have been checking ebaY for the purpose of comparison. (both brand new and auction items, mostly electronics and computer related)
In each and every case for new items, ebaY was more expensive than leading retailers.
For auctioned items, also more expensive, more costly shipping, lesser gaurantees/assurances that the item works etc, than for same or very similar items at another (more trusted) online auction site.
The biggest difference, a battery operated portable LCD TV with built in SD card reader: over 50% higher on ebaY than at Best Buy Outlet Center, NOT including shipping, which was more than 3 times higher on ebaY.
Then there is the possibility that the ebaY items were stolen, account set up with a fake or stolen ID, or would never get there, or that I would get tied up into some Paypal fiasco, with them demanding bank account numbers in order to use a credit card... etc etc, ad nauseum.
So, needless to say, there are probaly a lot of others out there who do comparisons and reach the same conclusion: ebaY and Paypal sucks: There are better, cheaper, more reliable, hassle free, and trusted places to buy or bid.