I think $600 is fair, collectors seem to forget that the parcels do not pack themselves, someone has to do it, and they have to be paid. Sorting out an individual order of, for example, 6 sets, could take up to 30 minutes, sorting the order on the computor, printing off a receipt, [if overseas sorting out the customs stuff], going to the stockroom to get the sets, building up the box and packing, checking you have the right stuff, print off a label, put on box, sort out postage as you have to weight the box and make sure it has the right postage costs. Even taking it to the post office or organising a courier collection.
I think we need to have a bit of empathy for dealers, if things continue they could be gone in 3 to 4 months, never mind no forum, no TS collecting as we know it now, fewer sets from fewer manufacturers, this could be the final nail in the coffin for some, as like most collectors they are no spring chickens, they could feel it is time to retire.