As Shiznaz and Danhalen do, I use a pair of Christophe straps. I pulled them off of a twenty or twenty-five year old Raleigh road bike and they have been great. Don't slip, no mechanical problems and they are in great form after two years of use.

But, I switch them out in the winter, since the weather tends to be wet. As people have said, leather is going to wear out no matter what you do, just like riding in silk pants

I use the Christophe's in the spring and summer and some of the fall. Then put on some black nylon straps that I think I grabbed off an old mtn. bike or something. They stay pretty stiff, especially after they get a bit of road grime on them after a few weeks of winter riding. They aren't the large-weave fabric ones but the kind of nylon where if the end isn't burned up you can press it together and form a tunnel down the middle (if that makes any sense. Wish I had a pic)

I'd save some your strap money for some other nice parts, use sexy leather ones in the dry months and nylon ones in the winter months. I'd spend $50 on a lot of other things before I ever spent that much on toe clip straps. I can't even begin to think about shelling out for some of those more expensive doubles.