$500 over invoice is pretty good.  That is $500 over the cost the
dealer pays GM for the car.  The lowest I  have ever seen was $150
over invoice for a vette sold by a dealer in the current year of
production.  Around here this time of year I see some advertised by
some low volume dealers for  $10k off of list or sticker price. These
are Vettes that have been sitting on the lot for a while and the
Dealer needs to move them so he can keep his allotment. They are
always coupes never roadsters and almost always silver or white with
very few options.  As for the GM Supplier discount , Most dealers will
tell you that Corvettes are not eligible for the discount, and if the
dealer honors the supplier discount , it is only applied to the list
price. So you most likely would get a better deal by looking for one
that is $500 over invoice.