well the new 60 Giga hash units are about to come out for only $1299.
And $149 for 4.5 Giga hashes.
http://www.butterflylabs.com/products/So based upon these performances, I would offer you 1.5 BTC
as 4.5/10=0.45=450MHASH = $14.9
Though since they aren't out quite yet, I add a convenience fee of 0.5
for total of 2 BTC.
Though my offer is an insult, sadly that's whats happening today.
If I were to buy this from you. It would take many many years to pay
back for itself, and perhaps never if difficulty goes up 10X