Pre-finished steel rails from Standard Steel Specialty
 

When I ordered my rack from Standard Steel Specialty, I asked if they could grind our rails also since they also make rails for elevators and such systems. Here is what Tim Oravitz (timo@stdsteel.com) provided me:

"Price for a 8 foot section of angle iron per your sketch would be $197.00
each F.O.B. our plant. Delivery is 6 weeks ARO. These would be made from 2.5
x 1.5 x 1/4 angle iron."

Not cheap but it is an option for those with rails.