What you say these have received good returns to investors, so can't as low cost, you can invest in some of the ICO project, and then select the hold 2 to 3 years, so when the time comes you almost is the lowest cost.
Of course at the first look it seems like the currencies with low capitalization are unpopular. But this is not entirely true. It is better to pay attention on the price growing tendency and how much time the currency on the market.