I don't think they make a permanent mulch all mulch has to biodegrade so it can keep feeding the roots of the plants it is covering. The best place I have found as a really good information source is your local greenhouse they have tons of pamphlets they can give you as well as their own personal knowledge.
I recently used recycled tire mulch. It generally comes in black, brown, or red and runs between $8-10 per bag. I laid weed prventive fabric down in my flowerbed and then covered it in mulch. Haven't seen many weeds but they still pop up once in a while.