USB miners sadly will be mostly to learn/have fun. You might as well get a original BE 333 mhz for cheap, as with usb stick miners they just cannot compete on price. Ultimately it will be for fun.
Good advice but I have one thing to add. You'll never earn enough on any pool to meet the minimum withdrawal amount or cover the withdrawal fees with a single USB stick. You'd probably need several dozen just to meet the minimum.
I'd also like to say that even if you had thousands of dollars to invest, you'd most likely never get a return on your investment. Just read two other threads in this topic to learn why. But the short answer is that you're about a year late to the game.
The last good investments were KNC Jupiters, Bitfury rigs, Antminer S1s, etc. from a year ago. But sadly, they are now obsolete due to the difficulty rise and cost of electricity. Newer miners exists and are much more efficient but they still will never be profitable to run.