Greetings, APUG:

My family does a secret santa thing for Christmas every year with a $50 limit for which I must provide a wish-list. I really want to ask for some kind of film or analogue-photo accessory. So, the question:

If you were going to try to get the most bang for your $50-buck, what would you purchase?

Details: I already own a Nikon FM2n with several lenses, a good incident meter, and filters. I like B&W film better than color, but I'll shoot whatever.