there is a certain level of expectation of listing accuracy from known auction houses like RIA, Heritage, LSB, etc. and that premium is worth it to me for their expert evaluations and descriptions.
the value of a collectible gun in my opinion retains some portion of those fees as it reinforces its pedigree to some degree.
taxes, transfer fees, shipping etc. are fixed costs for any gun purchased in similar manner or venue so I don't really consider them in the price of the gun but rather cost of doing business.
collectible opportunities are exponentially greater shopping on the national scale and those costs are generally much less than cross country travel expenses, fuel, lodging, time, etc.
private listings can be risky for representations of value not obvious in pictures.
as for this first year blackhawk, low three digit serial, and of course being a gunfighter length .357 in that honest wear condition, total cost seems reasonable to me (not something I personally follow the market on) and something I would have purchased if in the market for such.