Well- I have to say- I'm the queen of Ebay.
I love Ebay. I could never have afforded my bikes if I didn't pick em up piece by piece on Ebay- fortunately I have a gearhead friend who puts em together for me.
If I bought them from my LBS- and yeah- I know- I do try and support my LBS in other ways...I just dropped a hundred bucks today on assorted clothing,shifters and grease...I'm buying some more clothing next pay...
my one bike would've been about 1100.00 Cdn... I paid about 450, including shipping fees.That's 9 speed, Deore LX all around,Rockshox Judy XC forks...

I've bought 3 wheelsets on Ebay. and 4 frames ...plus various components.. They all arrived in excellent condition. I saved a substantial amount. Hey- I just got one brand new never used wheelset for- get this! $5.00.
course, the shipping is 14 bucks- but still.
( In this case I got a second chance offer- the winning bidder paid 29 bucks for the same wheelset. I was just horsing around and put a 5 buck bid on it...didn't expect to win it)

So- I'm sold.
Just make sure you check their feedbacks...stick with a company that has sold a lot...or you could check out some of the online stores that advertise in the bike mags...depends on how highend you wanna be. I figure I'm pretty middle of the road, but it's fine for my purposes. I am in the midst of upgrading my other bike to XT.

You can get some pretty good deals...especially from places that buy up liquidation stock, and part out the components instead of selling the whole bike. Sometimes it might be last years model- but who cares? The stuff is new and unused.

I've also bought used stuff- and I've never had a bad deal. But check feedbacks- that's imperative. Go back in their history and see what other stuff they've sold as well...

HTH

Kimba