I understand Drew's comment, however, the method of advertising "Buy 6 get 7 free" just sounds deceptive.  The argument that someone would buy 6 only to return it and buy 7 is a little out of whack.

For instance:  knowing that B6 would become obsolete in two weeks when B7 is offered, who would buy it or have time to learn or use it?  Those of us that have B6 would expect to pay a reduced price to upgrade - Drew is right about that.  Why not just say, "B7 is here!  If you  have B6, this is your price.  If you don't, you have X number of days to get it at the upgrade price, after that, it's full price."

This would stimulate current owners and intrigue future customers.  Buy B6 and get B7 free is almost "bait and switch."  The reality isn't any different, only the perception, and in marketing, perception is everything (why else would we buy bottled water at 3x the cost of gasoline?).