If this were my situation, I would get a quote for original erector, to disassemble and reassemble. Obtain second price from a masonry contractor to pour new slab on grade. Can you perform site prep for new slab? New property owner would have head-start in erecting his own storage building. If new owner hires the original contractor for a new building, you should receive a finders or referral fee.
The Nightmare:
It never looks as good, 2nd time. Trim can't be saved, not a big deal but a cost for sure. Yes, screws do reverse. But neoprene gaskets don't survive. If you have never disassembled a structure, don't have experienced help, well, most folks accept advice only when it is too late to be of value. But this is a big erector set, the exception?
Matching the screw holes in the roof and wall panels- very difficult, are roof supports , Metal tubes, the purlins? Requires marking location of each panel? Big PITA. Then setting a screw in a hole that already contained a screw, holding power reduced by 50 percent or More!. Yes, larger screws may be an option as noted. If you relocate screw holes, each existing penatration in roof is a leak!!!! You will be recaulking for the rest of eternity. Panel scratch and dent in transport/ temp storage, handling. Count on some loss. You fall, get hurt on project, got good health ins.? Income while recuperating? Presumes survival.
If you list the property w/ provision that building will be moved, the potential buyers will fight like **** to keep building, low ball purchase offer if building removed, boys just love their barns! I sold a property with a new 36 x 80 barn, no other structures, It would have sold for just as much if there was no barn but I lacked the motivation to move it. Are your support posts in or rest on slab. ?? You answered yes. Mine would have been simple, concrete piers with anchor bolt with steel post receiver for wood column at grade.
Now, have you thought through you options? Building Inspectors can be very difficult in dealing w/ relocations.close review of any structural damage. Your insurance carrier may require an engineer certification before binding coverage. Building insp may also require architectural stamp... all new costs!!!
But building is Not certified? Post below questions that meaning?
EDIT: vertical roof? So panel ribs run perpendicular to roof slope? So rainwater must pass over each rib? So there is always water or ice on the roof equal to the panel rib height? It does freeze at times?