classic33
Leg End Member
The way round that, money exchanging hands, is to tell them what parts* are required and let them buy them and you'd fit them for free.As soon as money exchanges hands you have a potential issue as it has technically gone from 'a favour to a friend' to a 'commercial' transaction'. Given the propensity for people to to sue each other in today's society you need to ask yourself if it is worth the 'risk'? If sued & without insurance then you could lose your house and other assets. You may say that your mates would never sue you -but if tehre is an accident their family may well might. Worth pondering on.. This is the reason why business have to pay out a small fortune in business insurance...
*Usually tyres, innertubes and cables.