I would say it depends on the model,
there are some good 28mm out of there (like the interwar earlyWW2 by Mpennock that are priced in a competitive way, other vehicles seems weird (ok there is a guy who asks 515€ for a Panzer I...

).
I have not yet figured out how every price is derived, but I think that some kind of vehicles are cheaper than others; and that some designers are better in reducing prices than other. For example and 1:56 Type89 is cheaper than a 1:100 Type96G...
To be quite honest I was thinking an open topped vehicle would have bene cheaper, but maybe there is something else involved (maybe the way it has been designed and the effort involved, it is a highly detailed kit after all).
It could be interesting to see how much the price could change with a solid cab (after all the bulk of available trucks/utility in resin have solid cabs and I do not see if you can add a drive without cutting the roof and then fixing it again.
Ok too much "mumbling"; it is a great kit. I do not use lorries in 28mm because I play with realistic scale rulesets (evil stab at bolt Action), but it is a great addition to the range of available vehicles for HM forces in World War two and a little after.