If this is your first time; Well done! Here is some feedback
I would have liked to be able to buy things easier, and have a simple pattern. Just seems like you did something like;
if (Input.MouseClicksButton = true): cost * 2.4543
Please forgive me if that isn't correct, but that's what it seems like. I was also stuck at earning coins for a bit. And once I saw my +1click cost go from 1K to 14K, I just kind of gave up on the game.
TL;DR:
Next time you make an idle clicker, consider making a pattern of some sort when buying items, and a counter, to show how much you have. Apart from that, very well done!