Harlow Rally Farmer Rip-off

Re: Detecting Rally Harlow Essex Sunday 2nd August.

1 day open rally on Sunday 2nd August in aid of our local scout group [...] The price for the day will be £15 on the gate [...]  As usual all finds over £300 will be split with the farmer and all govt treasure rules will apply. 

So the farmer gets fifteen quid and the oiks will potentially each walk off with pocketsful of artefacts all of which they value at less than £299,99 . Four of them to each pocket is 1196 quid they've walked off with, for fifteen quid down.