I have no knowledge of the details of this particular project, but have worked on similar projects before. Making new staybolts involves a bunch of work, including: sourcing material (regular A36 steel will work but isn't ideal if you're actually going to hammer over the ends the old-fashioned way, instead of just welding them); gun-drilling for staybolts that require a telltale hole; heading (forging the ball-ends) and slotting for flexible staybolts; and threading the body. Depending on the restoration facility... what equipment they have, how talented their machinists are, and moreover how much free time those machinists have... it often makes sense to contract out some (or all) of this work. In my experience finding the right material was a bit of a pain, but we were particular; we sub'ed-out the gun-drilling; did the heading ourselves; and the shop machinist (retired, a volunteer) did most of the threading. $31K spent wisely should be able to make a fair number of new staybolts.