It's very easy to see with basic math that BlockErupter boards will never, ever, pay for themselves.

http://www.bitcoinx.com/profit/
Estimates it will take 142 days to ROI.
This is increased from 119 days for last month.
During the last month the difficulty increased roughly 25%, causing a 25% drop in the value of mined work.
142/30=4.7 months
As the difficulty rises by ~20% every month for 4 months, you're going to be left with thousands in debt.

On the other hand, ASIC miners from BFL or Klondike will remain profitable until roughly Sept.
@$300 for 5gh/s and $200 for 4.5gh/s respectfully.

At their current price, products from ASICMiner are a scam.