I was in Graham a month ago.
(There is a local independent but it has a bad reputation in the trade; the reputation has it that it sells cheap tat, or faulty branded stock and if you ever have a problem with something you've bought there, don't bother trying to get satisfaction.)
So, I was replacing a WC siphon as the diaphragm was damaged and not worth repairing as the siphon was too high for the water level and I wanted the new one to be as close as possible to 25mm over the waterline. How it should be, in other words. WL was a little over 7" so I wanted an 8.5" siphon. I feel that on a low or high-level cistern, removing a siphon is no big deal, and that on a close-coupled cistern the close-coupling plate is usually starting to rust by the time the diaphragm fails so to change one without the other would be doing the customer a disservice. In this case the diaphragm had lasted 20 years.
So what wanted was a one-piece 8.5" siphon. Graham had a height adjustable siphon at some ridiculous price, or a 3-piece 9.5" siphon at over £16 plus VAT. They were out of stock of 8.5" versions. I told them that was a ridiculous extra hike to my customer's bill to not even really have the product I wanted. Just makes me look expensive without either myself or my customer deriving any benefit.
Toolstation had a 9" one-piece of a reputable brand for £4.76 inclusive in stock. Guess which supplier made the sale.
The other problem I have with merchants is that I tend to supply emailed quotes and I write these in the evenings, but the merchants are closed and cannot supply me with prices. I price my jobs based on what I can find on the Plumbfix website and then find there isn't the money in the job to allow me to buy at the merchants.