User Defined Subscription Amount

[blazin]

I would like to implement my subscription system, but instead of creating a fixed dollar amount, I would like the user to enter the amount.

My forum's income is more donation based, but the benefits of the donators last a year. I figured the subscription manager would be a good way to track it.

Usually people donate anywhere between $5 and $50. Instead of creating a bunch of subscription types in say $5 increments, I want it to be a text box where the user enters how much.

I searched and couldnt find anything on this. If anybody can help, it would be much appreciated.