Economics of mining today

[Thenen]

Question: if you buy one of these:

50 GH/s Bitcoin Miner
BitForce 50 GH/s Miner
$2,499.00

http://www.butterflylabs.com/

Turn it on 24/7/365...

How many coins could you mine per month (roughly)?

How much electricity would it cost (roughly)?

This is an economic question, as I am primarily trying to understand the motives and likely actions of miners - i.e., hording or selling of bitcoins.

Don't buy it, learn to calculate and you will understand better...