There are used stands out there but perhaps not in your area. I found this link and they have four side stands plus one bow stand for $500. I note though that at max extension they are a bit less than 5 ft.
NEW & USED BOAT ACCESSORIES
Perhaps if you contacted a local yard they might have some they'd be willing to sell? I presume you are looking at a long term project
otherwise a local yard might be willing to even rent or lease
them. Not too many individuals own their own unless they are doing a long term project
and many of those projects either last for years or infinity.
Edit: If there is a marine salvage
company anywhere around they might have them.