Reply to How many times did you regret buying second hand gear?

I had all of my camera bodies (40D, 5DII and 7D) purchased second hand on ebay, the most expensive one (5DII) I had examined before buying since the (private) seller lived only 10 km away from my home.
No regrets here on any of those cameras.

Regarding my lenses, there are three primes and three zooms that I bought on ebay from private sellers, only one of them (a 70-200 f4 L IS USM, my first purchase) was old and used and has focusing issues in certain situations, so I probably paid more for it than it was worth. Yet I don’t regret it, since it is a fantastic lens anyway, though I’m looking forward to replace it by a new one whenever i will be able to afford it.
The other ones were in a like-new shape, absolutely no regrets:
a 15-85mm (came along with the 7D), a 24-105mm L (kit zoom of 5DII), a 15mm fisheye, a 20mm/1,4 Sigma and my favourite lens: 35mm/1,4 L USM

Have a close look at the sellers, look for reasonable or fair offers, not the cheapest, and don’t buy when in doubt (unless you can afford the risk anyway) is what I recommend when purchasing on ebay.