i got a 2020 325 ci for $31k with no package, i realized on the 2002 coupes, don't be surprised to pay 1500-1650 over invoice.
Just quote him a price below invoice and see his reaction. i mean if MSRP with options is y dollars and invoice is x, then you quote like 200 less than x and see his reaction. If he is speechless or has a heart-attack then you get a fair idear of his profit-margin and can gradually work you way up