I thought that Trading Standards require that all RETAIL (as opposed to BUSINESS) sellers quote VAT-inclusive prices. Certainly your high street shops do. Feel free to correct me if I am wrong.
So is there an exception for on-line selling, or is it just certain businesses at the dubious end of ethics who are trying to see what they can get away with? Or mere incompetence by a web designer? Or something else altogether?
I know that if you are sure of getting the exact same item, to the correct specification, on time, the correct place to buy it from has to be the cheapest. However, none of that is necessarily so, and as they say, "buy cheap, buy twice".