Yeah good luck with that! I guess you haven't noticed, but the going price on the 5870 is returning to normal. Those cards really are a terrible buy even at that price unless you're short on space.
Absolutely wrong.
If you add up the costs for a server (bare minimum)
cpu- $30
ram- $10
psu- $150
mobo- $140 (if you know cheeper then this with 4 pci express then let me know)
hd- $15
PCIe x16 Extender Cable $12*4
5870 $190x4
= $1,153
(440x4)/1153=1.53 megahash per dollar(full server cost)
with 5830
5830 $110x4
= $833
(330x4)/833=1.58
So as long as you go the absolute cheapest route 5830 rig at 110 is better but not much so. If you add a case or more to the cost at all the 5870 at 190 will probably overcome the 5830.
It almost ties the 110 5830 at megahash per entire server cost at bare minimum. If you add a case or raise the price of the server in any way it will be better then the 5830. At bare minimum it is better then the $130 5830. Also this is better on electricity then the 5830 so they are not a terrible buy.