This is always the question of investing in a good time, when the cost is small and you will for sure get profit in the future. Bitcoin, Ethereum seems like currencies in which it is for sure you need to invest. But do not forget about much cheaper new coins, which have good potential, as some time ago it was some OMG, for example.
IOTA already proved me my good decision of purchase, wait the same from other newbes as TDS, BITS, hope, they will not disappoint me