Hi Giovanni
The MPT-5 was discontinued a long time ago, yet they still seem to be regularly available on ebay. (there's a new in box one I see listed right now as a matter of fact) So to answer your question I think there were enough of these tools made that they probably won't ever be worth a lot of money as a collectable, but they represent an important step in the history and evolution of multitools.
As such, no serious collection should be without one.
Bob