Altcoin mining hardware is only worth it if it can retain some value after you are done mining. So GPU/CPU mining or HD Mining (Burst).
You are better off buying some altcoins and forgetting about them for a year.
Mining is slavery.
Well I think hobby mining may
feel like slavery sometimes, but OP is only planning on spending 100-300 bucks so not like much could go wrong besides wasted time. Also, sometimes you can get a more in depth knowledge of the workings of coins if you are mining them. If you only have $300 I think you might be stuck with CPU mining with raspberry pis or something.
I agree though, that if OP is looking purely to profit, then it makes more sense just to buy $300 worth of low cap coins and hodl.
p.s. there is no "legit" anything in this space