I understand how to setup Zones to change the shipping price based on the sale subtotal. But after a certain threshold, in this case $250, we'd like to set the shipping to "Call for price". At the moment, anything over $250 is priced at $0 with the text "The shipping rate cannot be determined at this time".

This installation is not using real-time credit card transactions. It is setup for offline processing. So maybe I could just edit the text above? Would that suffice?

Thanks in advance for your thoughts.