Man they are worth what the market dictates, not what someone will pay for for something. My neighbours farm sold for $2200 an acre. The purchaser had a wad of cash because he was bought out by the mines. So he paid stupid money for $1000 an acre country. The same goes for sandman's. Some fool pays stupid money for a sandman in crap condition does not mean they all suddenly go up in value by 100%.
The bloke who paid over $500000 for that GTHO Phase 3 would have learnt that lesson the hard way.