Marketpress--let buyers (donors) enter in the price (donation amount)

Hello,

I am using Marketpress as a donation plugin as I have not found a donation plugin that allows for a shopping cart style donation. We have multiple programs we would like donors to be able to 'add to cart' so they can donate to various things in just 1 transaction.

I don't see a feature in MarketPress that allows for the buyer to enter in the price. Please let me know if that is available, and if not, would it be difficult for you to make the adjustment to include that for us?

Thank you.