Cheers bengasman. Does this mean if I give him the job, which he's since said is £525 to replace a gully, I'll have some scope to get him to lower his price? I'm not sure how plumbing etiquette works...
Varies from person to person. Taking myself as an example, my quote is the price. However, that is expecting normal working conditions. If the client offers things like: Do it whenever it suits you, in one go or 4 steps, that makes it easier for me, hence I could do something about the price since I can use as a "filling time job".
"Do the job, and I will send you a cheque in the mail afterwards", will result in a higher quote then money up front.
I am inclined to say no when people ask if I can't do it cheaper (under the same conditions) but am open to negotiations. That does mean the client makes the job easier/more interesting/more attractive in order to get a reduction. My last installation was a matter of: here is the key, there is a room to store your materials and tools safely, there is the coffee, there is the fridge, help yourself, just make sure it is finished before it gets cold. They got a rather good deal.
The next one wanted it fast, cheap, and the only time it was convenient for her to let me have a look at the situation was one particular day during office hours. Didn't even bother going.
But that is me. What your chap is willing to do, is up to him.