A few thoughts ---
For One, I fully believe that the D800's debut price was lower than it should have been and it was a decision by nikon to sell it as a loss leader to gain market share. Canon, who has the lead in market share, released the mk3 at the price point the d800 should have been at in order to lure canonites to nikon, and of course new users that would saw WOW at the big MP # - which has of course led to this whole price vs value debate here among all ya'll gear heads. I fully believe that if canon and nikon were on an equal level with market share, both bodies would have been at the same price.
With that said, it's no wonder to me that d800's and mk3's are popping up on the used market more frequently. Both are a year old now, so they aren't the newest greatest things anymore. Many bought either body hoping it would be their answer (and yeah, there are quite a few richie riches out there that buy a fancy camera because its fancy, you know, got to beat the neighbors and have more fancy toys). What happens next ,serious shooters that bought and dislike are selling in order to get a body that better suits their needs - as are the fancy people who have had the body for 6 months and didn't get the street cred they wanted, or did but street cred fades quickly so time to sell that toy to get some other fancy thing.
Either way, I'd say more and more used mk3's and d800's will hit the market over the next year, because that is the flow of things. I know one friend of mine who is having buyers remorse on his d800, he likes it for some things, but, wants to trade up to get a d3 or a d3s.
To the OP, one thing about those crazy deals is they disappear rather quickly. On another thread here I was bringing up my backup body thought process and whether it will be a second mk3 or a 6d. One poster claimed up and down that there is no reason to buy a 6d when there are refurb mk3's for $2400 (I have only seen refurbs going for that low, used ones I am seeing for $2799). But, again, you got to be at the right place and right time for the $2400 deals because the supply is low and the demand is high (too many damn people use that canonrpicewatch site...grrrr). There was one through adorama up yesterday for $2500, and where is it today, gone and sold.