The clock tower flyer was seen in BTTF:I.

I purchased this online

Though not terribly exciting, these are well made. The clock tower flyer is simply a photo copy of one of the props onto blue paper. I have heard that there is some controversy attached to this prop, as it is not really the one used in the film, but a "B" version of the prop. I have not even bothered watching the film to find out. Frankly, it's not really that big of a deal to me. I picked these pieces up a while back for a few bucks, and I think they're pretty nifty.