The goalpost is if this game is pay to win. Meaning the more you pay the more you win. It has an upper limit of $100 you can spend to max out 3 items. So let's look at each case.
Spending $0: having a <2% disadvantage against players with equal skills, if and only if your opponent has spent the maximum amount of money ($100).
Spending $100: having no disadvantage against anyone.
Spending more than $100: Nothing changes and there is no need to do that if you choose your items correctly for your main.
In my opinion, this is not pay-to-win. But to each their own.