-How do I explain all this to my wife? If she sees 600 dollars worth of computer equipment shipped to the front door, I'm a dead man hands down.
If you have a hard time justifying a $600 expense, then I guess it's a tight fit with your disposable income (you don't have to answer this, I know some people don't like to talk about their income)? In that case, I would recommend not getting the stuff. Only spend what you can afford to lose, you have to assume the worst (bitcoin crashes, everyone floods the market with ATI cards and their value plummets).
Personally I only invested my tax returns, which I felt was "extra money" anyway.