I was quite surprised to see that website have a pretty high rating on http://www.resellerratings.com/store/overstockdigital
Then I started to read some of the good "reviews" I noticed a lot of them are very short, with little detail. Can't help but wonder if they are fake reviews. It would be easy to improve your ratings at resellerratings.com with fake reviews. The negative reviews there tend to be much more detailed and realistic looking, though you have to drill down pretty far before you can start finding them. The negative reviews make is sound as if the seller is using a lot of the usual bait and switch tricks, lots of misinformation and, at best, selling gray market stuff that should sell for a lot less.
I also seriously question anyone who would offer a 5DIII with an EF-S 18-55 lens with... Or with a 1GB Compact Flash memory card (that would hold 40 or fewer images). It also appears to be a Dane-Elec CF card, which tend to be slow, and they show it selling for $49 elsewhere on their website. You can get 16GB UDMA fast Sandisk and Lexar CF cards from B&H and Adorama for around $50 each.
Usually you should be very suspicious of prices that aren't pretty close to what B&H Photo and Adorma in NYC charge. They are two of the largest volume, lowest margin sellers around... are rebutible, reliable... both have been in the biz for decades. Anyone undercutting their prices by very much is almost certain to be cutting corners somewhere.