If it's a hobby, I wouldn't even care about ROI, I'd just spend enough to amuse me.
From your post, I'm guessing it's still a business, and not really a hobby. Well then, you're late to the ASIC party. If you were to order one now, you would probably get it six months later, and have to compete with all the other ASICs that has been running for 6 months, driving difficulty up sky high... which means that you'll be extremely lucky to break even at all; if the price of btc increases in a linear fashion...
In which, to answer your question, yeah, I'd spend a few thousand bucks buying a couple of metal/plastic bricks for my hobby.
