[mr.pure]

Well done on the find and all that but you're living in a dreamworld with your £800.
A quick search shows them almost entirely selling for around £180-£240.
The longer you wait, the more of them will have turned up and the lower the prices will have gone.
The Royal Mail knows about these things and probably set the price based on the long term market rate for a coin with 200,000 in circulation.