I used "Rider's Choice" on eBay
. They are in Alabama. I hesitate slightly to recommend them though because the quality seems inconsistent.
The saddle I bought was one of their "GW Crate" Wades (see picture below). I loved it so much, and it was so well made that later on I bought a second one.
The second one wasn't quite as nice. It fit the same and everything, but it was like the person who built the first one was a pro, and the second one looked like it was made by someone less experienced. There were some nails that went through the tree and were pushing the skirts out a bit, the seat leather had some small wrinkles, etc. So I was disappointed in the second one. I still kept it and I like it, but it just wasn't made with as much care as the first one. The first one was awesome!
They are really nice to work with though and will help you find a saddle that fits.
I would start by making a wither tracing of your horse, then if you look at used saddles, new saddles at the store, or decided to go mail order, either way, you can have the wither tracing checked against the gullet of the saddle to at least get an idea if it looks like a good fit. Just take the wither tracing with you everywhere you look, or if you go with an online dealer, see if you can send it in. I have never used this store, but they sound like they have good customer service and will help you find a saddle that fits. I believe they have wither tracing instructions there too. Western saddles Sold; Billy Cook saddle, Circle Y , Tucker, Crates & used western saddle