I would recommend that you check out Cannon refurbished, the 6d is probably the better camera for only $1,599.20. If you don't mind spending an extra $575 you could get the 5d mark iii through Cannon's loyalty for around $2375, which just requires you to send in any broken Canon camera that you can find on Ebay for around $6.
No, its a bad deal! $1200 might be ok from a private party where there is no warranty. Don't fall for the blank warranty card included, you need to have a bill of sale from a Canon dealer for your warranty. If you are set on a 5D MK II rather than a 6D, get a refurb. They usually have low usage, and they have a 1 year Canon warranty, as well as a 14 day return rights.
They will be on sale this Sunday, its only a small discount, so I'd suggest trading in a old Canon film SLR or power shot that is broken. You will get 15-20% off the Refurb price, the amount varies. With CLP, you can also get a lens with it, and a discount off the package, which makes it a bargain.
Call them and check it out. When you are ready to buy, you will need to give them the serial number of the old camera, and then send it in using their post paid shipping label. This is for US customers only.
*Any* quick research will show you it isn't - the 6d is cheaper and enhanced in many aspects (see http://www.canonrumors.com/forum/index.php?topic=11309.0) ... but your post shows why I didn't buy a used 5d2, the prices are relative to the original price and don't consider the fact Canon now has the 6d on the market.
Afaik is 5d2 vs. 6d is only better at: cps, shutter rating, shutter speed, body durability (but both aren't outdoor bodies, so it doesn't really matter).