8800= expensive, marketed to the business community who is more likely to pay the price.
8320= less expensive, marketed to the same people who bought the 8100 who would have a serious issue with forking out $500.
secondly here is the price on ATT curve http://www.wireless.att.com/cell-phone-service/cell-phones/pda-phones-smartphones.jsp same price when all is said and done.