Straight To The Point

It almost seems acceptable for companies to advertise one price on their web site, but then announce that its actually a different price when you come to pay for it. The usual excuse is "sorry, the website is out of date". Why is that okay? It's obviously deliberage to lead you on, and once you've gone through all the hassle of contacting them and attempting to pay for it, the customer (myself included) just say "oh, alright then".