Allow Buyers to set minimum for offers

Hello,

We are using the Classima theme and the Classified Listings plugin. We have disabled the price from being shown and would like to only entertain offers where the user sending an offer has to state the amount they are offering and this needs to meet a certain amount for it to be met. I can see for the email to seller that there is name, email and message. So Is there a way of adding a price field too and also the seller being able to state a minimum amount they would like to see for a product so they could entertain the offer.

Thanks!

The page I need help with: [log in to see the link]