Whilst there is no denying the truth in Anebel's reply
you have said that you only do dressage competitions once or twice a season, so I don't see the need for a top of the range saddle that's going to last 50 years (your horse won't!) Therefore having an affordable saddle that you are happy with is important. If you get one with an interchangeable gullet at least you can put it on another horse if/when you get another horse. There is nothing wrong with a Wintec, if there was, they (the brand), wouldn't be so popular. And, as I said before it is from the same company that make Bates, just a different brand name, everything except the material and price is the same and Bates is a very good brand.
Dressage saddles are perfect for schooling and long distance riding, you don't need to get one with the thigh block, they do come without but IMO go for the thigh blocks you will really appreciate it once you've got used to it.
Yes you do need a proper dressage girth, a normal girth is far too long as dressage saddles have very long girth straps so that the buckles and guards are out of the way to allow you closer contact with your horse.
Webnut, you have perfectly pinpointed the train of thought that led to my posting this thread!
I don't exactly have great showring ambitions, I'm just delving into classical dressage as a way to improve my riding and my pony's condition, education, and ability, and a correct dressage saddle sounds like it would do a lot better for me than my AP. My horse "came" with a nice leather roping saddle, but it's too wide for him, so I'll probably try to sell it and channel the money into the dressage saddle fund.
I can't wait now for a break from school so I can go to the tack store and test some of these saddles! They have a good selection of used saddles, but not specifically used dressage saddles (at least that I have seen), but according to their website, they do stock a couple of Wintec models. The discipline isn't extremely popular in my area. I can probably count on one hand the number of dressage saddle's I've ever seen in person
Thank you to everyone again for the wonderful advice and insights!