Thank you for playing!
The main problem with the pricing is the fact that it solely depends on your performance, I see it as a cursed game design problem, since waves are not random, the amount of money you get is fixed, which means that if for example, a wall you built breaks, you will probably rebuild it, but for another player it doesn't, so they have more money to invest into more expensive utility. This issue is clearer due to the fact that the game doesn't have that many waves, but an expanded version would probably have a smaller issue with the economy from this problem.
But still, I'm glad that you enjoyed the game and didn't face such issue :D