I visited SMC bikes Sheffield last w/end, 2 airhead 'custom' bikes on offer, neither particularly very good, yet one was £8k.
Speaking to the manager of the business who spotted my 65 in the bike park outside, he told me unmolested airheads were fetching serious money as the chop boys didn't want to spend a lot of money getting the bike right before chopping them up and adding more cost before trying to sell them. This Sheffield dealer was shipping airhead customs to London mainly with an occasional local buyer. He told me to 'never' sell my bike, it will be a real investment in the future...