From my limited knowledge I think that the cheap coins are pretty much a crap shoot. However, since you spread out your money it's not like you'll lose almost everything unless there's a really, really bad turn of events for the coins.
If $20 is just pocket change to you and/or you could afford to lose some of it then I think it's not a bad idea to try this. I'm pretty sure you'll almost certainly be able to get most of it back due to the way you spread the investment out. If you're lucky you could double your money and reinvest in other coins, cash it out and get a meal at a restaurant or convert it to BTC and order a pizza on pizzaforcoins
If I weren't so cheap I'd invest a bit myself for the heck of it. I'll personally stick to mining for now since my electricity might as well be free.