The resin cost difference isn't the issue, and isn't that much overall. The greatest difference in why epoxy isn't used much in production boats is the manufacturing process. Polyester can be left inhibited between
layup periods, where epoxy must be prepped between layups. This is labor expensive. Epoxy works best where full
layup vacuum bagging or infusion is done. This is expensive. Vinylester requires tighter
environment control, and this is expensive. If the temp and humidity is off, vinyl can really mess the
bed.
Mark