Without seeing more it is hard to say. I'd lean towards using a brass nipple vs the galvanized steel or, extending the copper over to eliminate it...
As for the $150 charge for a 10 minute job that is not entirely unreasonable I charge considerably more that that here.
A plumber has overhead costs that far exceed the 10 minutes of labor that you see...
- How did you find the plumber? Advertising costs money...
- Either he or, someone else took your call and scheduled it... Again it costs money...
- Becoming a plumber requires years of training including schooling and an apprenticeship, and ongoing training... Again costing money...
- He then drove his truck and tools to respond to the call... The truck and tools again cost money both to purchase and maintain...
- The plumber provided the part... Again time and money to maintain an inventory...
- He drove to the call and looked at it either waiting for the city to shut off the water or, a return trip... Again his time is money...
- He did the work, guaranteed the work and also has insurance to cover liabilities from damages cause by leaks... Again costing money...
So you see $150 is quite reasonable...