Letgo at you a one man shop? How many calls like that can you or do you make in a day?
Is that include a markup on material?
For me the gfci is probably the higher cost $25. No markup that’s $145 that covers your time at the supply house, the 20 minutes roughly one to job and for some reason you try and build a relationship with that customer and you are on the job way longer than it takes to do the job. So let’s say 12-17 minutes to do the job and invoicing and that relationship building it’s twice that. I see it being slightly more than being an hour total.
Do you, if so how, allow customers to supply their own material?
I still have a my EC stuff in WA and did that for a couple years but I'm working at a 3 man small shop here on the oregon coast that I do bids for along with the actual jobs
Here's how I try to stack my days more or so the same
2 small 1 hour or less service calls and a small remodel or service change.
Rough or trim on a big job and I do 1 or 2 calls around it
Hot tubs or car chargers with a lot of pipe use up most of a day but a small one I'll stack with 1 service call
Doing service calls won't make you rich but they get your name on their phone and fridge as the go to person. Most I've done in a 8 hour day is 6 but that only works if they're all simple. Best way to make a decent amount and keep yourself productive is to plan on a couple hours max in the day doing small calls around a bigger project. I also do what I can to make my installs cookie cutter and avoid trips to the supply house.
Don't stock anything but white and if you push decora for kitchens you don't need many trick plates. Upsell what you have you could even end up selling to a person who didn't know they wanted the "pretty square switches". Outdoor pvc stuff I use the same 20 parts in a big sorter. Have a smattering of Blanks and boxes but don't go crazy and go for the slider type boxes for new and old work and 4 squares for metallic and surface wiring methods.
Only sell for small jobs 1 or 2 types of can or wafer light don't over complicate it. I like to sell the flat flat wafers but the 3 man shop im working with here likes the beveled that need to be away from a joist or truss. Either way only sell one. One install and always sell with a dimmer if you can.
Don't stock keyless fixtures stock the cheap halo disk lights you can sell them for more and the people will think you're not selling a poor cheap looking product even though total cost is near what a keyless and a dimmable led bulb are.