Setting the price of an asset through API

As a challenge to learn more, I am attempting to figure out a way to create a custom donation price system so that an end user can enter a price they wish to donate to a game / group or other entity, and then they will be prompted with a purchase for that price. I originally planned to do this using a Heroku hosted Python server that the game server would send web requests to, which would then send a request to the ROBLOX server. However, as far as I can tell, there appears to be no API for this officially leaving the only method being to forge actual website requests.

My questions about the topic:

  1. Is there any API to set the price of a Developer Product?
  2. If not, is it within the rules/TOS to make requests manually?
  3. If it is allowed, how can it be achieved?