2BTC for 300MH is still too much, even for the average geek who are not expected to be too deep into mining... 2BTC is 200 bucks for a tiny 300mh unit.
Its about the same price/performance as 7970.
1 * 7970 $400 = 700MH
2 * Block Erupter $ 440 = 700MH
Now think about a miner with 4 * 7970. It consumes over 1000W. You need 8 * Block Erupter to reach the same speed, but the power consumption is way under 1/10. Same goes for power consumption and heat...
But the same doesn't go for resell value.