If the current exchange rate holds anything above 2btc (preferably 5) a day would be acceptable.
with 40 x current difficulty you would need to invest at least 10 000 USD to mining hardware (based on current ASIC hardware pricing
Damn, that makes it a bit out of my reach. The highest investment I was considering was a little single. That would be about $700 with shipping. Considering what I would earn at current difficulty (13btc) that would make daily earnings about 0.325btc(@ 40x difficulty). That about 4$/day so it would take 175 days to recoup the investment. This isn't going to make me rich
I'm planning a btc project too so I'll keep to that for now. Don't think i'm going to invest in mining. I'll check up on the matter, still interested but think I missed the mining boat..