I just ordered one of these On Course Ladies Ashby Show Coat - Statelinetack.com
Mostly because they were the cheapest I could find with decent reviews, but man does it fit like a glove! I tried a couple on when we were at the Quarter Horse Congress last fall and all of them were too baggy through the middle. I was counting on having to get this one tailored after I got it, but the fit is perfect. They do run a bit small though. I had to order a size up.