Look for the things that aren't obvious, that are typical or tied to specific event or period. Y2K stuff, for example. They are tied to a specific date and will be discarded quickly. Or, if 'Baywatch Hawaii' is a long-running success, 'Baywatch' stuff. The bottom line, according to both Brown and antique guru Pake Zane of Antique Alley, is that you must care about the non-monetary value of these artifacts.
Telephone book covers.
Things taken for granted and overlooked, likely to be tossed out and disappear. If you enjoy it, and it made you feel good inside, then it's worth saving. The key is to keep whatever items you collect in mint condition. One recent change, noted Zane, is people buying collectible items as Christmas gifts for others, where before, collectors bought for themselves. Click for online calendars and events.