I don't know if this help any...
I recently visited an really out of the way tack store and the owner had an extensive antique tack collection that she showed me. LIke 150 saddles alone, and some dated back the the very late 1800s. I asked her did she ever know their vales, since she buys and sells occasionally, and she mentioned there are appraisers out there (I suppose google might help) and she researches and watches what they go for on ebay too.
She didn't mention specifc appraisers, but said something about they travel sometimes to really big shows or events and people will take stuff with them to be appraised.
It does take some digging around in the internet to even find out what some of the saddles are and saddle repair shops can sometimes help with identifying what you have.
I also want to say I remember her saying to have something prefessionally appraised she has shipped items and paid some hefty appraisal fees, but if the saddle or object sells for a high amount, it is worth it.