Oh I know what your talking about I think UMS used to have a cheaper version, but I havent seen them out in a few years.
I do have the MDC ultimates and I LOVE them. I dont ever have any knee or hip pain after riding. If you can hold out and save up for the expensive pair... DO IT. They are sooo worth it. Ive had mine for about 6 or seven years and they are still in amazing shape.
Keep your eye on ebay too... always some neat things that come up. Oh maybe check the tack shop consignment areas
~If horseback riding was easy they would call it football.~