quandry/ conuundrum of same-aged "regulars"

there exists, a fine line, between being friendly with customers and being friends.  i often wonder when/if it's okay to become friends with customers of the same age. seeing as that work is all i do (not in school, haven't embraced any pastimes of social relevance) the most i interact with people in my age group is...well...at work. making their coffee, grabbing a pastry. maybe chatting up some new album or movie or asking about what they are working on. but can it ever be more than that? or is that awkward?

how does one go about befriending a "regular"? does it come off as stalker-esque? do they even WANT to be my friend? does it seem like i'm flirting? desperate? lame???

i think the worst aspect though, are the regulars still in school or working real jobs. then i just feel inadequate in comparison--"look at me! i work at a cafe for a living! wanna hang out?"

argh! is it simpler than that? or is it just a sad consequence of working a service job that friendships with customers are just plain out of the question???