Get yourself a nice usb powered hub, and a RPI as a controller. Then by some GekkoScience compacs. They simply are best BTC mining usb sticks right now. For learning this route is very good.
Only thing you need to be aware that chances of ROI are pretty much none unless you sell it someday and made money on sale.
Thank you for your reply. All I need to do right now is buy a GekkoScience miner and a usb powered hub. I have a spare RPi lying around so this shouldn't be a problem. These will make a great tool for educational purposes. If I then decide to sell them, I would do so by listing it at a price a little bit higher than what I have bought them in order to ROI. But that would be very unlikely since I will keep them for time sake.
I should mention there is no guarantee with ROI. Sidehack is making a pretty sizable 2nd batch of compacs. So there are more on market, you might not be able to sell for higher... and you might be able to hard to say.
I know i sold some of mine when he was out and it worked out great as people wanted a product that was between production runs. Not all will get this lucky.