Old thread so I doubt the OP is still around. In general, if a retirement party is for someone you hardly know or rarely interact with, then deciding to attend is the first thing to consider. Attendance is never mandatory. I would talk with co-workers to see what is common practice if for some reason you don't already know. I would expect in most companies, you either pitch in for a group gift or the company pays for it. I highly doubt individuals would each be expected to bring a gift on their own.