Some missing information here
What is his usual trade? Labourer/have a go at anything simple man, would be a lot more economical than a c&g qualified high end joiner for the same job.
What is the level of risk of the job? And I don't mean falling off a ladder, I mean risk of arguments over paying(!), getting parking tickets, tools stolen in the area, drilling through pipes, broken tools, ceilings collapsing, getting sticky from a partner for doing their mate etc. These are all things that happen and need to be covered by what they charge.
What area of the country? The rates for labour vary massively, South east and North east are completely different worlds.
How did the conversation go before hand? Was it, Hi I hear you're in the trades, please can you do this job? Or, how much would you charge? I know it's awkward discussing money but tradespeople do it every day so they would be happy to estimate or explain their pricing.
I think being"done" is more of a feeling rather than describing what actually happened, but I'm sure you can handle things better next time something similar comes up.