I've been looking carefully at my collectibles and every one spotted over the last half hour or so was a common one. At last I got a rare one! As I had thought, it was sold for $50.

I wondered for a while if there was a new bug that was introduced in the new version 1.00.01, as I was pretty sure I was getting $5 for common ones and $50 for the rare ones earlier. I am a little less sure about the uncommon ones; it might be $15 and it might be $25.

EDIT: Just got an uncommon one; it's worth $15.