CMOR is selling it and they set their pricing. I think if honest they might tell you their costs are higher dealing with the MM3 format and don't want to cut their margins. Either way what they charge is what they charge, it is their product and sales program. I personally like the C-map bathy for price/value depending on the area in question. If you haven't contacted tech support and asked for sample screenshots for a particular Lat/Lon, you might want to check out that bathy if pricing is a concern.