There are many ways to figure the cost of an item. There is fair market value, replacement value, value of use, insurance value, and others. Each has to do with unique situations.
Without these hives, this beekeeper has no way to produce income in the spring. He may of lost pollination contracts. He will lose an entire years worth of honey production building hives up again in strength.
Just because you can find hives cheaper elsewhere does not tell the story. Can he find hives with clean comb, with no applied chemicals, in December in Pennsylvania?
If you have a particular car stolen, say a limited classic edition, worth more than the average car, do you settle on making the guy who stole it give you back any car. "Hey....you had a car with 4 wheels, and I gave you a car with four wheels" does not hold up in court. Having a classic stolen, then saying you can find a cheap replacement model on eBay for far less then the actual value of the loss, is not right. 4 wheels does not equal 4 wheels.
If you figure these hives had 60-80 pounds of honey at 6 dollars a pound for local artisan honey, that is 360 to 480 dollars in honey. The bees are worth at least another hundred if he needed to buy a nuc or package, and then there is the woodenware. Throw in a year or two building up the hives, drawing comb, etc., and why would 500 hundred dollars in loss be inappropriate?
Can he replace these hives in time to not miss a pollination contract this coming spring? What about honey contracts produced by his particular hives? He can not buy another persons hives and then market honey coming from his own hives free of chemicals. If I take a 5 dollar piece of equipment to shut down a production line, the loss is not 5 dollars. It is the potential loss of the production line not running, and the losses could be in the hundreds of thousands of dollars for reporting and insurance purposes. You do not settle for 5 dollars of loss.
But go ahead and kick the guy when he is down. Here a beekeeper loses his hives, and other beekeepers are nitpicking some amount of loss and thinking 500 dollars is too much to quote. I know the guy who lost the hives. He has a unique coffee, tea, and herb business where he sells at trade shows, fairs, and markets. What he lost in potential sales is more than some replacement cost of buying someone Else's hives. And going out and buying some cheap replacement honey this year while the hives builds up, is not an option.
I'd say his loss and the value of the hives is more than 500 dollars. And I bet under the circumstances, if this happened to you, you would not be happy being paid the asking price of some other hives being offered out there.