As a disclaimer up front, I work at a Running Specialty store.
I agree with most stuff on here that the highest price shoe does not mean it's the best shoe and you can find high quality last year's models on sale. Depending on the person, some people need support, cushion, ect. Some people can put on anything and go. Not everyone has the strengh/biomechanics/ect. to be able to run 800 miles in K-mart shoes but there is a middle ground somewhere.
In response to buying online, it is going to happen as that is the world we live in, but if you are going to go that route (which is fine), do it and live with the consequences. Going into a store to try them on and ask 50 questions about the shoe is pretty disrespectful. If the current online retail trend continues (in every industry, not just running) which it will because the consumer gets a cheaper price because the online retailer or shoe company doesn't have the overhead (rent, salaries, ect) of a brick and mortar, there probably won't be running stores around anymore to try things on or get advice. Also, a lot of local road races, either put on or sponsored by Running Stores will start to go away in anything other that Major Markets.
Not saying that online shopping is the devil and you should always buy at Running Specialty, but there is a cost of going for the lowest cost. Not trying to go Lorax, but I'm as curious as everyone to see how it all plays out.