I can PARTIALLY accept the price, i.e. £10 first, then I will send you the Tutorial and then you read and grasp it to decide it's PRACTICAL worth, OR = WORTLESS. Then you pay £15.
IF WORTHLESS, then I refund the £10.
And again, there is a crucial issue. Who (or what) will guarantee that you refund me (or anybody) if your method isn't
working?
Since though you are so sure, it will be much better to offer your method for free to some reputable members so they test it. If it's working, then they will give you the money that you want. If not, you won't get anything.