Try http://bit.ly/r7o0fw They have delrin and acteal sheet and rod in many different sizes and thicknesses. I machine many parts from acetal and always comes out nice.
You could also try teflon since it has the lowest co-efficient of friction of any other plastic, however it is a little more expensive and hard to come by these days. UHMW is great as well because it has better wear resistance then the teflon and should last along time. Both materials however...
Delrin is great for machining and is a very tough material. Great place to find it is http://www.iplasticsupply.com/materials/acetal-delrin-celcon-basf-pom-pomalux-sheet-rod
UHMW is a great material for sliding applications. Also try teflon is has the lowest friction of any plastic. Try http://www.iplasticsupply.com/materials/teflon-ptfe-dupont-halar-ectfe-fep-sheet-film-rod
Try UHMW or teflon. They both have great wear resistance and have low friction of any plastics. http://www.iplasticsupply.com/ is a good place to start.
Delrin is a great bet. It machines well and is self lubricating. Try it and it should work fine. I usually buy mine from http://www.iplasticsupply.com/materials/acetal-delrin-celcon-basf-pom-pomalux-sheet-rod for making bushings and other little pieces for my cars.
Try cutting with any normal cutting tool. It should be ok. I buy abs a lot for making odds and ends and it always comes out great. Try http://www.iplasticsupply.com/materials/abs-cycolac-absylux-royalite-sheet-rod. They have a whole bunch of ABS in stock in lots of thicknesses and colors