I've gone 2 routes.
I contacted a Saddle Maker/Fitter and he came out to my barn with a van/truck full of saddles, where he placed on his back after assessing him first. He of course, grabbed one's that he narrowed down to after assessing his back.
After he found one that fit my boy well, he had me ride in it to ensure that it fit me well, and he watched me ride in it, seeing how my body was placed and how my horse reacted to it.
He cost $100, it was well worth it. I learnt a lot from him and that's when my saddle fit passion started.
The second route I took, I went to a local tack store that a saddle maker/fitter owns and runs. She knows my horse well and when I told her I need a new saddle for the both of us, she pulled out saddles and placed them on her wooden horse for me to sit in.
The one's that worked well for me, she placed to the side, and the one's that put me in a not so productive position, she put back. Then that weekend, she brought out all the saddles that were put to the "Good" side, and placed them on my boys back and assessed them. The one's that didn't work, were put back into her vehicle, and the one's that were narrowed down to a great fit, she left in the barn.
She then had me ride in them to see how I worked in the saddle, and to see my horses reaction to them. The one's she wasn't impressed with, we took off and those were put into the vehicle - out of the whole lot she brought out, it was narrowed down to 2.
I loved them both. I loved how they put me in a fabulous position, I loved how my horse moved in them, I loved how well they fit him. What made my decision, was one went on sale, so I bought that. She also threw in leathers, irons and a girth.
I ended up buying a Marcel Toulouse Legano - and I couldn't be happier.
If you want help, I'd contact her. She's a vast of knowledge and can help you out. www.classicsaddlery.com