I have to say having ridden in Sprengers and non-sprengers there is a big difference, the Sprengers feel much better. They are definitely worth the investment. I have managed to find a top supplier of Sprenger products and at a resonable price! Seriously Equestrian have a really good range of...
Mark Todd Gisbornes are really good. My favourites are the Pikeur Luguna breeches. The cheapest place i've found them is at Seriously Equestrian who i recommend:
http://www.seriouslyequestrian.com/shop/pikeur-lugana-breeches/
They are so comfy, I can't recommend them enough. :o