I went for the cheapest option and I was well surprised how well it worked out. I bought the Oxford 1st Time soft panniers, cost me about �50-55 and it was well worth it! Done about 4500 miles around Europe in July and didn't have nay issues with them.
I was also worried about them catching fire or melting so went to B&Q to find some sort of heat proof tape or mat. I ended up buying a piece of plumbers soldering mat, something like this:
http://www.screwfix.com/p/rothenberg...ring-mat/54910
I cut it in half and stitched each half to the inside of the panniers. Actually I just stitched to the straps and they were just hanging down but the mufflers kept them in place. I haven't got a good picture but you can see them sticking out here and there (the square bits)
As soon as I put them on started worrying about them starching the mufflers and they did. The picture below was just after a few days
After about 3000 miles
I managed to restore them pretty well with a few scoth brite pads. I used Autosol on the pipes which has done an excellent job!
Next time I'll put the panniers on I think I'm going to wrap the mufflers in some sort of heat resistant tape
like this OR buy a couple of R&G protectors. They're about a cm or taller and should keep the panniers away from the exhaust.
Hope this helps
S.