Sounds slightly high based on my experience, but not outrageous. Plumbers are also in high demand at the moment , so you likely paid extra from that.

I also think you are making some wrong assumptions about the cost breakdown he gave you. He may have been at your house for 6 hours, but that hardly accounts for a lot of the backend labor that goes into a project like that, including buying various other materials needed for the install since the equipment does not come with all the necessary piping and valves needed, and then going to pickup all the necessary materials, potentially at multiple different suppliers since some materials are hard to acquire at the moment.

His statement about his supplier being more expensive than HD is absolutely true as well. Almost all equipment and tools sold by HD or Lowe’s are of lesser quality than the same exact product sold from a contractor supply house. That’s how the big box stores make huge profit , they basically pull a bait and switch on unaware homeowners.