CNC Companies

http://www.emachineshop.com/

I've used eMachineshop to cut 200 plastic bases I needed for a project. Pretty happy with the results and pricing. I used their (proprietary) CAD tool which then can price an order and place an order.

http://www.mqast.com/

Here's a company that specializes in low quantity runs and prototypes. I don't know too much about them, but it seems like that fast quote system might be nice.

Protype, Reston