what is going to be the cheapest cryptocurrency to invest at present and get double future return from it?

Cheap not always have future don't see from that, please fix it. You should research crypto from all source and take final analysis as your rules. Investment goals not always profit, some people use it to test strategy and increase their performance. Get double is good but investment is not easy like people say, you need hard work and capital to make it happen. Think again and see you next time.