Another factor that needs to be considered... in the US, shipments from China and Taiwan enjoy a "most favored nation" status... i.e., there is no duties on imports from these countries as a general rule. I don't have access to a TSUSA to determine if our pen kits fall into that category, but suspect they do. Many other countries don't have this luxury and have very high customs fees, VAT, duties, etc... depending on the origin of the goods... when the vendors here buy in the volumes they do, the cost per kit, landed, duties paid is only pennies whereas in other countries because of the import charges, the prices will/can be considerably higher...
In relatively smaller quantities, you can ship from an individual to an individual as a non-commercial shipment or even as an unsolicited gift and circumvent a number of the taxes. A shipment from a commercial enterprise to an individual will flag this as a commercial shipment and trigger the duties, taxes, etc....
I'm thinking it might be difficult for an individual to front the monies for 500+ kits over a number of kit styles and wind up sitting on a couple thousand kits for a while before they could move them out.... we appear to have a much much larger market here in the USA than a lot of other countries - I reach this conclusion by looking at the general memembership of IAP and other pen groups - our membership is by and large very heavily slanted towards the USA. Our second largest membership group appears to be Canadian.