The Topup feature is great, but I want to disable this so users don’t have the ability to manually set the amount themselves.

What would be the best way to just set static options for users to select from on a different custom page?

For example: I want to make a page with just these 6 options the user can select as buttons:
500 coins for $5
1,000 coins for $10
1,500 coins for $15
2,500 coins for $25
5,000 coins for $50
10,000 coins for $100

Clicking on one of these buttons would take the user to the Checkout process and add the coins into the user’s wallet when they’re done.