I have commented on this fact many times.
Over here in the UK, rare OOP stuff sometimes fetches £40+ easily.
But every now and then you do get some bargains.
I picked up a full unit of white wolf Knights for £2 plus £2 postage.
All thanks to the seller listing them as dwarf knights

There appears to be no interest by GW to either cash in on this phenomenon or to re-release any of the OOP stuff.