Ever wondered why online shops are cheaper? Could it be because they don't have to pay for retail space and staff, and they don't have to waste their time serving freeloaders who go and buy elsewhere after they've spent their valuable time serving them? What will happen is that you and others like you will drive the bricks and mortar shops out of business. Once that happens you'll only have online shops, and how will you work out what fits then?
Alternatively, why not recognise the service your LHS provides, and support them, rather than being unpleasant to them?
I recommend to anyone who asks, and lots of people do ask me, that if they want new skates and they do not know the size, go to a good LHS with a good range in stock, and if they have something that fits properly, buy from them. If my good LHS goes bust, I'll be in big trouble.