A lad in my local co-op always says "alright Bud?", which I find rude. I've worked in retail before and was always taught to just say hello or good morning, then if you need to get a customer's attention you can simply say excuse me, or add a sir or madam at the end if, from the feel of the conversation, you feel it appropriate.
Maybe I'm just too British, but when I'm in a shop or Bar spending money, I like to feel valued. Calling someone mate or bud is not really giving a customer any higher status than a non-customer.
When I lived in Luton in the late 90's, I heard all sorts of weird things like "alright Chief?", or "geez" (short for geezer?).
Humans are a strange bunch