I would list the coins highest priced first, lowest price last. If you had chosen 4 coins or so, I would have suggest investing 1x in the highest priced coin, 2x in the next lower priced coin, then 4x and 8x. To get x, sum the numbers 1, 2, 4 & 8. Divide the total funds to invest by the sum, the result is x. This approach focuses your funds into the lower priced coins that will rise by a greater percentage.

With a larger list, you might create 4 price LEVEL categores, calculate your x for the categories, then apportions funds amoung the coins in that category.