"…They also have digital multimeters for sale at the same price (£9:99) and again these look very robust and good value for money."
There is a 'standard design' multimeter readily available from China, usually marked with the number '830'. Mine has proven robust and reliable for many years now. I see that you can get them off Ebay at a low price of £2.25p, which includes postage from an address in the UK.
I can't see how shops are going to compete…