Here's a full table of the dies used in the extrusion process. The specific shapes cut into these dies determine the cross-section of the extrusion. Different shapes make different parts. What you don't see here is an example of an actual shape (because they're trade secrets for each company producing parts).

I'd read somewhere that the cost of producing a die was around $2,000. If that's accurate, you're looking at about $36,000 here.