U serious lowMicra? only $150? Lets break it up...average person with proper tools and lift about in a workshop:
Labour removing and reinstalling gearbox, plus adjustment approx 3hrs
optional = removing flywheels, machining it, changing rear engine seal another 1 hr
Then plus parts cost ie, clutch kit, oils, etc...
So i dont know how ur actually making a living on $150 clutch change? Even assuming the customers supply all the parts including oil. Most shop would charged $70-$80 per hr average that would be approx $250 at minimum.
If i was a shop owner i wouldnt Even touch it for $250 as you have to factor in the fact that if something ****ed up not anything due to your fault ie, faulty parts supply by the customer etc. then it would be over my head pulling it apart and redoing it as i would have a reputation to keep. Therefore most if not all workshop would prefer to supply and fit the part themself.
I would assume an average cost of $400-$500 to be reasonable for a clutch change. Thats just my opinion.