I Have for sale an older dressage saddle that might be of interest to you.
Its a Thoroughbred saddlery Luhmuhlen model probably 20 or so years old because they do not make them anymore and havnt for some time but it is in fantastic condition all it really could use is a little dye. Has never had nor needs any repairs. Its been used lightly, just has some fading. I would say its a narrow tree, but its not super narrow but more so than a medium tree. Its made specifically just for thoroughbreds. Its a 17.5 inch seat(runs a little small IMO). Im asking 350 for it, there are some on ebay
for 500 that have had repairs done on them so I think its a good deal, I just need a saddle that is a little bit wider for my horse cause its just not the best fit. She's QH/TB so she's a little too wide. Its very comfortable, made exceptionally well, soft strong leather, well taken care of and very well balanced. It has wide panels underneath it, cutback pommel and a round gullet and lots of clearance for the spine. If your at all interested it is listed in the tack section and I can email you more pics. I love it but it doesn't fit my horse now and if it can help someone else then I would part with it so I can get one that does.