This is supported in OFBiz as Price Rules. You can set these up in the Back office/Catalog Component under Price Rules. Under the Conditions you will set a condition for the product and another for the Role Type you want the customer to have. I believe you will have to enter the RoleTypeId and not the description(some are different..all upper case/etc.) so check the RoleType entity to be sure.
Also, check out the following article:
http://docs.ofbiz.org/display/OFBENDUSER/ProductsThe following is especially important from the article:
"If there is no list price, then no price rules will be run for the product. The default price will be returned as the price for the product. In addition, competitive price and average cost will be returned as additional available information, in case the calling application uses it."
-CJ