my advice
get a list of the work and the prices
you have met the customers, so thats a good sign
i would try and see if the guy will let you work it with him ONCE, that way you can earn 50 % of the taking ( he can knock it off the bill ) and you will pick up advice and valuable tips
i only ever pay the rounds worth, so 500 quid worth of work it 500 quid, as the guy wants to sell, you want to buy, i have been lucky though with that