There are sometimes a few legit reasons for people paying "more."
They have eBay bucks or an eBay coupon that still makes it cheaper than anywhere else (ie, 20% off coupons are rare, but awesome if you get one). I've occasionally bought something off eBay that was higher priced, but with my coupons, was much lower than anywhere else (I love the $10 off $25 and 20% coupons).
They are an international buyer. They will pay higher than most US retail prices (especially since those retail sellers won't ship internationally) and then can get certain products much cheaper than a local store in their sells.
However, I've sold things in auctions that for whatever reason have gone way above what you could pay in a retail store to American customers, even if they had a 20% off and eBay bucks to use.
And then there are the pawnshops that are on eBay selling used, beat to hell Snap On for $5 off list price, OR (as I've actually seen before!!!) a good condition used Snap On going for higher than list off Snap On's website. Stupid.