I'm a movie buff and what I collect are DVDs. The goal is to profit from them at some point the other reason I collect DVDs is because I love movies and just must have a physical copy. I have a huge collection at the moment and in time I'll start selling my Disney classics for some really good cash.
I used to collect basketball cards. I have about 3000 of them in storage. I am curious to know how much it is worth. I guess I will have to sit down with a Beckett's one day. But I was almost obsessive about collecting basketball cards back in the day.
I like to sort through and collect change. Here in Panama, we have American change circulating through our own change as well and on rare occasions I stumble upon silver dimes or wheat pennies.