Setting Minimum Ticket Purchase?

Hello,

I am looking to see if there is a way to  set a minimum number of tickets that can be purchased for any given performance. 

We have an event that is seating in pods of two, and thus need to make the minimum number of tickets a patron can purchase 2 or in sets of 2. 

I though it could be achieved with a pricing rule, but am coming up short.

Any assistance would be greatly appreciated. 

Rhea