Owning your own home

Business acquires materials, combines them with labour, total cost of job is labour plus materials plus a premium on those materials. That quite comfortably describes both a bike shop and the operation of a tradesperson we’re talking about.

The key difference is that with most building jobs you have variations during the period that the service is being provided.

If everything is known upfront and a fixed price is agreed, it makes not a jot of difference how the cost is broken down into labour and materials. The hard bit comes when you are pricing changes - that's where you might get a bit miffed if you found that there was "hidden profit" in what you thought was a straight recharge for materials.

I'm coming at this from the perspective of working in a highly regulated industry. If I ring up a counterparty and say "do you want this bond, I paid £100 for it", and in fact I paid £95, then I could get absolutely reamed by my regulator.

Amusingly, it’s also fairly accepted practice with bike shops that if you provide the materials yourself the labour actually costs extra!

Also correct, some do, some don’t, I just says we can’t offer guarantee/warranty as it was not purchased from us.

E.g. chain provided by customer snapped due to its being faulty, no warranty, pony up for a new one.

Otherwise be happy to replace the chain on the spot and send the faulty one back to the supplier/get credit if purchase from us.

I don't charge extra or refuse to fit online bought parts, never have (bike shop).

HOWEVER. If the parts you brought in, because it was a banging deal on a non UK registered business has the wrong front mech type, cassette size or mismatched R/L crank arm lengths, then I'll still be charging for the time up until that customer mistake was realised. Because if I'd ordered it, I would have checked it was the right part for the job, thats why you make margin, to cover the grey areas between direct working on the job (hourly) and what it takes to actually get the job fixed.

The squabble over the past 5 pages highlights this quite bluntly, you aren't always in the customers house, hands on the tools, but you are getting the job done*

*Trades that piss me off are the ones that turn up at 8.00am, bang on, nice, then get a coffee, then a smoke, then at 8.30am (peak rush hour) realise they need to go to 7 different builders merchants for stuff for your job, their next job, and collect the misses argos' click + collects. At 11.45am they turn back up and get to work.
THIS IS OK. So long as I'm not being charged for those 3 hours of driving around when almost all of the items collected have nothing to do with me or my job.
Am happy to pay for their time to go and pickup stuff for my job though, not like its gonna get here on its own.