How to alter Marketpress to so the customer can opt to pick up the goods in store.

Hi All,

I’m running a retail store as well as an online store and I know that at some point customers will want to pick up the goods they order online in store.

Is there an easy way of removing postage charge if they check a collect in store option?

I’m currently using Nathanonn’s Epic plugin for custom fields, i just need it to remove the postage charge if checked.

Any Ideas?