Is there a way to drive the Price of Item A to be $0 if Item B is entered on a sales order

We have a requirement to present the price of an item at two different prices depending on the addition of another specific item to a sales order.  These items are stand-alone finished good items.  For example:

Scenario 1:

- Item A entered on the sales order by itself (or other items entered that do not influence the price of Item A based on our business requirement)

- Price of Item A = $1000

Scenario 2:

- Item A entered on sales order

- Item B entered on the sales sales order as well

- Price of Item A = $0\

Thanks for any thoughts or suggestions.