what is going to be the cheapest cryptocurrency to invest at present and get double future return from it? 
Stellar and Cardano seem to be leaders in the coming years. So you can safely invest in these coins and wait for happiness, which is bound to be.My choice is also ADA and Stellar. OK, I will add here TRON. TRX seems to be a very good cryptocurrency that will become the 2019 gainer. Nevertheless, the guy who asked this question can find the cheapest alts on https://coinmarketcap.com/