Just my Opinion-via-Experience (yes, I know I'm a bit of an Ashinine), but I have never seen an entire Lot of Molds sell as the Lot, in all these years.
Figure-in shipping per each, and offer to sell individually, maybe discount a little on multiples, at best...just my $0.02, Born from Extensive Observation.
Also, a little more info on the molds would help You and Potential Buyers...is the BT 3.75" the 660? Is the BT 2.5" the 662 (2.75")?...dotdotdot.