The links you posted do not go to the saddles directly.
There are three different HDR Dressage saddles. Henri De Rivel Paris Dressage Saddle - Statelinetack.com Henri De Rivel Dressage Saddle - Statelinetack.com Henri de Rivel Pro Buffalo Dressage - Statelinetack.com
I assume you mean the second above, though the third is cheaper and better quality than the second. HDR saddles are decent, mid-range saddles. The Pro and above lines are decent and about the same quality and construction as the Dover Circuit saddles. Circuit Dressage Saddle - Dover Saddlery.
Either would be a fine choice for you, but tree size is an issue for the horse that you ride. Since he's not your horse, buying a fixed-tree saddle might not be a good idea. You may end up leasing a different horse in the future, or buying your own. That is something you should keep in mind.
Wintec has some nice saddles that have changeable gullets, that give more flexibility to fit. They are perfectly suitable for showing in, at any level, and might be a better option for you. I'd suggest demoing the saddles to find out which one you like riding in best and which one fits your boy best. They are all in your price range. Wintec Isabell Dressage Saddle - Dover Saddlery. Wintec Pro Dressage Saddle with CAIR Panels - Dover Saddlery. Wintec 500 Dressage II Saddle with CAIR - Dover Saddlery. http://www.doversaddlery.com/wintec-...1-15628/cn/94/
Thorowgood would be another option. They have a changeable gullet and are nicely made saddles. http://www.doversaddlery.com/thorowg...1-15754/cn/94/
Your other option would be buying used. You can find a VERY nice used Dressage saddle for around $1,000. Some Kieffer models have trees that can be adjusted by a qualified saddle fitter, should you end up with another horse in the future. County, Albion, Passier, and Stubben all make excellent Dressage saddles that you should be able to find your price range.
With buying used, it's best to buy from a consignment shop (online or in your area) that has a trial policy, so you can be sure the saddle fits your horse and is comfortable for you. Many shops can look at wither tracings and help determine which of their saddles would be the best fit. If you're interested in going that route, I can give you a list of online shops that will work with you.