I am on week 4 of the Couch to 5K program, with the goal of running in my first 5K on June 5th. I have been running in my regular tennis shoes that I also use for aerobics and that sort of thing, but I think that I might want to get a good pair of running shoes. We have a bunch of running stores around here, but never having bought a pair, I don't have a clue where to start. What should I look for in a store? Is there a chain that you would recommend? About how much can I expect to pay for a decent pair of running shoes? Is there a break in period? Anything else that I should know?