Join Date: Dec 2010
Location: southern Arizona
Borrow some saddles and see what fits her. If you plan on keeping the price under $1000, I'd suggest borrowing some Abetta saddles or Big Horn.
Western saddle trees vary between company, but are usually consistent within one brand. Also, western saddles are pretty forgiving. Unless they are a grossly bad fit, and unless you ride for many hours/day, you can probably get by with a so-so fit for a while. Try to find one that has a slope in front that matches the slope of your horse's shoulders (behind the actual shoulders, of course) and isn't too long.
It really isn't possible to make recommendations from an Internet post. Borrow a bunch, if only to put on her back and see if it matches OK. If looking used, make sure you can return it if it doesn't fit.
"Make the right thing easy and the wrong thing...well, ignore it mostly."