Have you looked at used saddles yet? Outside of my city, there's a really awesome place called the Tack Collector, and you can sometimes find lightly used saddles for half-off! There might be a place like this where you are living, and I'm pretty sure your local tack stores may even have used saddles.
Sometimes they also offer package deals; I got my Mondego (relatively expensive brand!) saddle along with a set of stirrups and leathers, a bridle with reins, and a D-Ring snaffle all for only $1800. It fits well on just about any average horse I put it on, with the right padding.
If your budget is only $300, you might have to go the synthetic route. I've never seen even a used leather dressage saddle (unless it's absolutely craptacular) under $500. But some Wintecs are relatively
comfortable, and I've even seen brand new ones for $200. I still don't think I'd ever buy one myself; leather lasts a decade if cleaned and cared for properly. Synthetic... not so much.
I don't generally shop by brand, so I can't help you there! Generally, the more expensives saddles are
the more quality and comfy saddles, but you can still find a cheaper saddle that is functional. Find something that fits your liking; there's lot's of different styles and shapes of leg flaps, and decide if you need leg blocks (prices can get higher, though). Seat size and fit is important.
When you sit in a dressage saddle, it should fit something like this
(notice the position of the knees, and the dimensions of the seat compared to the rider). Have a friend take pictures, and listen to what you body is saying to you!
And, of course, it must fit your horse! You're shopping for two here! You best bet is to have your trainer or a professional check the fit and see if it's putting any pressure on his back. Generally, you can manipulate it with half pads, etcetera, if there isn't enough wither clearance or if it puts pressure on places. Make sure you are able to return the saddle if it doesn't work out
Oh, and I'd also recommend looking for one that has a straight/backward curving flap
, rather than a forward-set flap
. It can change your leg position dramatically, and makes you work harder to get a good should-hip-heel line.