Clipper sticker/catalogues on the back of Tris are cool but loads of POTF Palitoy Trilogos got them, so they aren't as rare as people believe they are. The mini catalogues are (at least imo) the least interesting of all the different stickers and offers Clipper used too.
I certainly wouldn't pay a premium for one nowadays (having seen so many) and really most people just see them as a bit of a bonus if they turn the figure over and find one.
The prices stated just above are pretty close to what I would have said but maybe you find a focus collector or a Clipper collector that's willing to pay a bit more than ODB's estimates.
Three years ago I bought a Paploo for £40