Why do you want to buy altcoins below $0.50? It doesn't matter how much costs 1 unit. Doesn't mean that it will go up 100x. What matters is the market cap. Something that has a market cap of $10M has a higher chance to go up 100x than something that is already worth $1 Billion.
If you're looking for a coin that can go up x10+ take a look at
Aion and
Aeternity. If you want to go for lower market cap coins check
Hive Project.