It's funny that on a 4000 you think 2.5% is reasonable. A 4000 lounge suite would have a much higher margin.
A builder doesnt need office and staff - if he does have that , it means he is doing volume building, and scale of economy in how he charges should be kicking in and actually becoming cheaper . He still shouldnt be fleecing people by making false commissions on other peoples work for which he actually does virtually no work.
Its actually funny how you think it has to be a %. You see, payment for work is based on an hourly market rate for a given skillset , ie a fixed quantity, not a %. Do you think people who work for a company get paid a wage based as a % of the profits? No, they are workers, not shareholders.
The $100 I made up was based on an hours work, which I would estimate is all the effort most tradies would put in when engaging a subby.
As for the warranty red herring, lets face it, if the subby stuffs up, he will be back in there re doing his work, else sabotage himself by getting no more referrals and a bad name.- pointless if you are trying to work in an industry. Risk? Hardly, not in the main, and you know it..
No idea why you are bringing a lounge suite into the discussion, totally irrelevant.