If it makes 3m/hour your better off using it and not selling it because it won't sell for that much more + you need to get it verified but to put a price on it, try to sell it for like 10m or something like that.
Depends on the guide. is the method bottable? You could earn a lot more. How detailed and is the money per hour stable? Several factors need to be taken into account when determining the price of the guide.
If leaking it wont ruin the $ rates then sell it for around 10m after getting it verified, if it would ruin the $/hr rates then just keep it to yourself