On 2006-10-19 22:09:58 +0100, Nick2 said:

My Halstead combi packed up recently - the diverter valve stopped working
so no HW (normally caused by a split diaphragm). There is a heating spares
shop down the road from me so I enquired about a repair kit, they quoted
28 ukp plus 6ukp carriage plus VAT with a 3-day lead time for the
diaphragm.

After a quick Google I found BES in Birmingham offering the diaphragm for
4.50ukp or the complete valve for 23.25ukp (plus 4.95 shipping plus VAT).
I ordered the complete valve as the boiler is 13 yrs old and on its 2nd
diaphragm, the goods arrived next morning. Now fitted and all working

The most expensive I found was actually online - uk-plumbing.com at
64.40ukp + whatever delivery + VAT for the valve.

How on earth do these people maintain business?

Greater volume, smaller margin than the other guys.

Don't assume that on line places are automatically cheaper. That's a
phallacy. Other similar examples are the cartridges for shower
valves. There can be a 3dB difference in price easily.