I made a set this summer and posted a thread on my other favorite classic Mustang forum ...
http://1969stang.com/forum/index.php?/topic/56854-upper-control-arm-support-tools/Made a second set for a friend ... took around 55 minutes including clean up. Material cost per set is under $4.00 using 3/8x4" CRS ... computer says we bought 24 ft in 1998 and there was under 16 ft there so 8 ft must have been used at some point.
One set at a time I think I'd want $40 for a set ... make 3-5 at a time maybe could charge $25-30 / set.
Had I not had material here, I would have likely gone a different route.
McMaster Carr skips over the 1-5/8" width so you would need to use 1-3/4", which is where your average joe would likely buy CF Steel bar in small qty. They sell it in 6", 12" 24" 36" & 72" lengths.
Using 4" wide like I did you could get 3 sets out of a 24" piece ($43.95 / 3 = $14.65 each set material cost.
or
Using 1-3/4" wide you could get 2 sets out of a 36" piece ... $21.95 / 2 = $10.98 each set material cost (plus UPS shipping cost) and would save a little labor since the 1-5/8" width is only critical at the top where it grabs the upper arm; could leave the lower 5~5.5" the full 1-3/4" width. This is definitely the cheapest route to go if only making a coupe of sets at a time.
Buying a 72" piece would not be a huge savings ... $37.85 / 4 = $9.47 each set material cost; however UPS may charge an oversize fee on the 6 FT. package, so could end up being more expensive this way.
Time could be further reduced if they were made from 3/8 x 1-5/8" stock, which surprisingly does exist according to my steel supplier book. Comes in random 12 ft lengths, so you'd have to make a whole bars worth (8 sets) at a time and likely order the steel with a material stock order to get it delivered cheap. Material cost would maybe be $4~6.00 each set this way and labor maybe 10-20 minutes labor per set if you were to make 8 sets at a time.
Certainly don't want to go into business making these myself, but just trying to guess at a cost difference between a guy buying material to make one or 2 sets himself vs. done in bulk.
Doug