Trying to gauge price on vintage piece

[dannyp]

So I'm looking for a watch for my girlfriend's 30th birthday which is around the corner and would like to find a vintage stainless 36mm piece from 1983 for her (year she was born). I'm pretty indifferent between an OP and DJ but would like to get a sense of price for vintage, in good working condition, from reputable seller. Also, if anyone could point me in the right direction I'd appreciate it.

We're in Chicago, so could look locally around here but with the right reputation I could do this by phone/email as well. While it's obviously important to prove authenticity/service record they absolutely have to be able to prove that it was a 1983 piece because it's the real reason for going vintage. Thanks in advance for making me a hero :D ;).