I have moved my Gold Crown III four or five times. Took it across country one year for my kids to use.
From the photo posted I would check the rails to make sure they bounce right. Make sure you have all of the parts and check against the assembly manual. You can get a manual online if the owner doesn't have one. Make sure that none of the threads are cross threaded where bolts connect.
If you replace the bed cloth, replace the rail cloth as well. It is no more difficult than replacing the bed cloth. If you check around online you can save quite a bit buying new cloth from a good dealer. It usually comes with rail cloth and that is what you should buy.
Consider getting a small hand held metal brake tool from Home Depot for accurately stretching the bed cloth.
You can move the table with a Dodge Caravan. All of the pieces will fit in one run. I use packing blankets (or similar) between the pieces of slate (lay slate flat in the van). In the past I have used cardboard between the slate with no problem. You do need a blanket on top of the last piece of slate. This keeps the rails etc. from damaging the slate during transit. Just be careful. It take two men to carry the slate.
Store the slate flat when you get it home. This keeps the edges from getting small cracks. If chips or cracks develop use Bondo to fill and sand with a finish sander.
With two men here are my estimates:
Dis assemble and load in Dodge Caravan about two hours.
Reassemble about four hours including leveling.
Install bed cloth about two (maybe three) hours depending on your experience
Install rail cloth about three hours (lots of staples).
It is best to have help from someone who has done this before to avoid stupid mistakes the first time, like bumping the slate on corners etc.
$400 is an excellent price. I sold my 25 year old GC III for $1,000 when I retired to Florida about four years ago.
Thanks for the thorough info. I'll keep it in mind.