I'd diversify my risk if I were you. I started about a month ago with building Adafruit's PiMiner project, getting 3 USB BlockErupters, then I found a couple of used BFL Jalapenos for a "good deal" (stupid to get these I know, but the markup from BFL's retail price was halfway sane by Ebay standards), and now I'm looking at KncMiner and Bitfury preorders next. I'm also thinking about buying BTCs when they hit these temporary ~$70USD valleys and selling when they go back up in value. I doubt I'll see ROI on what I've spent, but it has been a fun hobby so far.