There is a plastic injection molding shop called Protomold in Minnesota whose business model is based on this thinking.
You can upload a 3D solid model of your plastic part at their website, and if it's well-designed, they will quote it and take your order on-line; CNC machine a mold from aluminum; and deliver you a few molded plastic parts the next day, with 5,000 to follow if you like them. Not stereo-lithography prototypes, but actual ABS plastic production parts. Not $40,000 and 12 weeks to deliver hard steel tooling, but $2,000 and overnight to deliver injection molded parts from an aluminum tool. Radically revolutionary in that small world and a sign of things to come.