The problem is if some thing goes wrong, like a re-call, one you may never know about it, and two you would need to pay to have it replaced. And you would need to go through all the hassle of getting the replacement.
But likely you will get it done slightly cheaper, the normal is for an electrician to buy at trade, but charge you retail, the difference means if nothing goes wrong, he makes more money, but if some thing does go wrong, he needs to replace FOC.
When customer supplied parts prove faulty there is often friction where the supplier blames the electrician and the electrician blames the product, when the electrician supplies it, the supplier to the electrician does not want to loose the trade, and is more inclined to accept returns.
Electricians trade on their reputation, they do not want bad reviews, so it is better for them if they have full control, so if they have enough work without taking on jobs where the client wants to do part of the work, or supply parts, then he is better off back healing those jobs.
So you are looking for an electrician who is short of work, and the big question is why is he short of work? Which is why best to avoid any electricians who use companies to find them work, trusted tradesman, checkatrade or any other firm who finds work for the tradesman, if he needs them to find him work, likely not much good.
There are exceptions, the guy who has worked for years cards in, and decided to go sole trader, but taking a chance.
It does not need to be an electrician, all other trades are the same, I would never dream of buying paint then looking for a painter and decorator to apply it, well maybe an exception where I work on a heritage railway and the paint colour is really important to match the colours used by the Great Western Railway, but that is a special case.
