WARNING WARNING.......
First - all the deals that are too good to be true - are. Lots of gray market, bait and switch and bogus ratings..... when buying from a store check:
http://www.resellerratings.com/rlist-s1-n2.html or other reseller ratings
eBay has lots of stores selling camera equipment - some good and lots that aren't. Look carefully at ratings.....lots of negative and even 'mutually withdrawn' are signs of problems.......
LOTS of problem stores operating under multiple names. Especially out of Brooklyn. You'll find these places all the time as "recommended" under bogus shopping comparison sites - which THEY set up or pay for referrals from.
Gray market stuff - NOT intended for sale in the US market, imported from elsewhere - can be a big problem if you have a problem. Some sellers have their own warranty, others have nothing. Nikon for one won't touch non-US cameras in their US centers. Other places try and sell you - at extra cost - the batteries and other accessories that should come with the camera. Some will sell you third party lenses (which may be OK from your point of view but know the value of what you're getting).
Having said that there ARE good sellers..... but usually their prices will not be 'super' bargains (because few are going to sell product at a loss).
Places like Cameta (near Nikon's East Coast service center) sell lots of refurb product - shorter warranty, up to you if you're comfortable with a refurb item...... Some specialize on gray market - again up to you if you're comfortable with that.
Can't speak specifically to Canon - but I'm sure you have similar situations.
final note - ANY store that wants you provide a phone number for 'order confirmation' is likely to try and hard sell you expensive 'accessories' or upsell you... and if you won't go along, they'll be out of stock....
These comments apply to stores..... individuals have their own risks.... feedback is important - as is a history of selling similar items - (no recent feedback and drastically different items can signal a fraudulently hijacked account)