If they offered you kayano, then you clearly need a support shoe. I go to a running shop about once every 5 years, get my gait checked and talk with them about the type of shoe I need. I then buy a pair from them. When I need to replace them I just shop online, where you can pretty much always grab a bargain. I don't usually spend more than £50 on a pair.
Interestingly there was a study a while back which discovered that the more runners paid for their shoes. the more likely they were to get injured! (I haven't read the study, so don't know what else they took into account).