Have we really reached a point now where unless you've been doing it for a while or can put a large amount of capital upfront it's just not worth it?
You've already got 0.5BTC. If you want to purchase an S3, you'll also need a PSU to run it. Right away you're spending more than that 0.5BTC. Right now, the S3+ is 0.58BTC and has an MOQ of 2 units. You might find some local resellers who will do one unit at a time, and if you're already got a PSU, that's good, but if not, more coin out of your pocket. Once you figure out how much you're going to spend up front, and how much the unit(s) will cost you to run ask yourself if you think that S3 is going to earn back that and more. If yes, then go for it. If no, then don't.
I've bought and sold hardware and mined with it. I'm ahead of the game, so it can be done