I know you were looking for appraisers, but I would really look into Eastern insurance firearm insurance, it will be cheaper than adding to your homeowners or whatever kind of insurance. And covers your stuff anywhere. At home, in your car, in a hotel, etc. There just has to be forced entry, so if you leave your car unlocked, they won't cover. But any forced entry and you are covered. $100k in coverage for all your firearms, optics, suppressors, accessories is like $340/year. You can of course add higher coverage if you like, I think the minimum coverage is $50k and its around $150/year. They don't need any serial numbers or itemized lists unless any single item is over $10k, so any single firearm or single optic, etc is over $10k by itself is all you have to let them know about ahead of time.
I had to make a pretty large claim with them earlier this year, I could not be more pleased with how they resolved the situation. I will be with them for forever for my firearms coverage. In my claim they covered: firearms, optics, mounts, suppressors, slings, backpacks, binoculars, rangefinders, tripod, part by part custom ar's I built, any aftermarket accessory added to a gun. Literally everything. Oh they will even cover your tax stamps on your suppressors.