Regarding the Peter Green/Gary Moore to the best of my knowledge Gary Moore wanted to sell the guitar as it had become a bit of a liability. The insurance premiums for the guitar were getting daft, and touring with it was impossible. As aluded in a previous post, Gary wanted a dicreet sale to a collector who didn't want to make a profit from the guitar but wanted it for their collection. A sum not unadjacent to £300,000 was mentioned. Once Gary sold the guitar it was very rapidly sold on for a rumoured $1,200,000, which is how it ended up at Maverick music, although whether they bought it outright or it was a consignment sale I don't know.
One of the reasons that the guitar has fetched so much money is that the provenance of the guitar is not in dispute: a major issue with many instruments.
Hopefully this will clear up a few issues.