I see that the DBV is now assembled in China. That wasn't always the case. TokinGLX has previously posted pics of DBV components in varous stages of assembly, sitting along side SSV components in the CO factory. I'm sure the current 'assembled in China' deal is a result of vastly increased demand for the DBV. This doesn't mean the vape now compares to the generic, cheap vapes made in a Chinese factory where they put different names on the same vape and ship 'em out to distributors and resellers with no warranty. I'm sure the components and other materials for the DBV are the same as they have been. I know that was the case for the brand new DBV that I had for evaluation about a month ago.
As for the reasons for the price difference between the two units, I'll give you the info straight from an email that Steve (the owner/designer), sent me in Oct. of '08. In addition to the reasons listed, he also said the SSV bag cost was 5 times that of the DBV bag. There have been a few bag changes through the years though, so I don't know for sure it that's up to date or not.
The SSV costs more in production time. More cuts, sanding and filing. The base on the SSV is made out of metal not plastic. This costs almost 4 times more than the DBV plastic base. The SSV is also a powder coated base adding to the cost. Also, the glass- The knobs take about 15-20 minutes to make. They are not cheap to make. The DBVs knob is about 1/30 the cost of the SSV konb. All glass costs more. Also, for some reason the SSV takes way longer to produce.
The heating element and electrical components are are the same for both units. If you cut corners here, you risk losing your profits (and reputation) to warranty repairs/replacements.