Surely not all trades people know everything about their trade? They weren’t born knowing all aspects, and when new products arrive they must surely need to sometimes ask how it works what goes with what ect. I work in a job that requires me to use plumbing, electrical, heating, cooling and mechanical skills and because of customer requirements or requests this leads me to have to ask the relevant trade counters for their assistance in what products are best suited for the application. So far I have not had a problem when asking advice and long may it continue, i’m just trying to do a job. As for trade prices, if you are not the end user of the product then you ought to be able to get a discounted price.