Building a Bitcoin mining rig
When you build a mining rig you need to take into consideration are you going to ever want to use the GPU's for something else? If so buy with them brand new and make sure you get it the GPU registered since they will be cranking at 100% at about 75C. If not get them used, I prefer this method as you can buy a 6850 for about 75 bucks if you do it right. Also need to realize bitcoin or the BTC is profitable but there are alt currencies that are more profitable to mine right now. There is PPCoin and Litcoin, these will yield you money. It is no over night get rich scheme but with a decent setup you could make about 10 dollars. Then once you have coin you can monetize the coin itself at a cryptocurrency exchange by selling it when its high and buying when its low. This is not hard, you just need a lot of patience.
Also ASICs, you need worry not, Avalon and Butterfly labs are the makes but there has only been 1 or 2 confirmed Avalons. But BFL is very questionable, they said they shipped but this was to reviewers and developers. Only reason they shipped something was because of pressure from paypal. No pool operator(s) have confirmed on of these BFL ASICs on there pools, so I myself am very skeptical. Not to mention Sonny (BFL owner) who has been to jail once for fraud is very good at pulling long con's. I am not trying to detract from the work BFL maybe doing, its just I have been taught if something is to good to be true, well then its not true.