Its a good deal if you can get someone to go for it.
We have a lot of customers who supply some or most of the parts. It is not that big of a deal as long as they tell us what they are supplying up front so we can add in the things they are not supplying. Often customers do not even realize how much stuff is missing.
Some customers do this because they think they get a better deal on parts then we do (almost never true). Others because they want multiple panel builders to bid and since some panel builders get much better deals on at least some parts, they want it to be "fair".
Some of that's true, but I think this is more of a scenario where somebody needs 45 ft of wire and the electrician cuts it off of a 500-ft spool.
Or you need to use some connectors, whether it's Romex connectors or EMT fittings or whatever it might be. The electrician is going to buy them in boxes of 25 or 50 instead of the customer going and buying a two pack or a three pack.
Same with devices. Buying them in 10 packs makes them cost less but you may not need 10 for that job
When that customer wants to buy the materials, all he's thinking is that he doesn't want to pay a markup. He wants to win on that exchange.
But then let one of his parts fail and he'll call and say "hey, that stuff you installed last time isn't working. Can you come out and take a look to see what's wrong?"
And that same guy will get his panties in a bunch of you tell him the warranty does not cover his parts, so if it's determined that his part failed you're gonna give him a bill at $120 to show up, $140 per hour with a minimum of two hours
That kind of guy is hoping to save some money, then give the liability to someone else.
No thanks. I wanna smack people like that