I have had great success dealing with Modern Plastics. They do not
have minimums, and they have a sale section that has lots of smaller
pieces of the kinds of things you want. I got my delrin rod from
them. Their url is modernplastics.com. You can do a search on the
item you want, or send a price quote request. They are based on CT,
but ship everywhere, including internationally.
I found them while looking for a better plexi for making matrix
dies. They have a product called Spartech Polycast Cell Cast
Plexiglass that is truly wonderful to work with. Easy to saw and
file, and it holds up under the pressures of hydraulic press work.
hope that helps,