Now THOSE things are gonna get you in real financial trouble! You'll find all sorts of cool stuff to add to your evilBay searches! 
Like they didn't already. Would you believe they are just for 'research purposes'? Pass the tissues.

(I speak from experience)
Wow. I will need a new house before I can fit that many (and the resulting buys.)
Hey, you have two 1972. Want to sell one?
And btw, do you collect HP Application Notes too? I've returned to that pursuit, after yet another painful reminder that many people are destroying these wonderful old documents, in the process of 'scanning' them. Cutting bindings off, to feed through auto-feed scanners, etc. Invariably making really crap quality scans, so really just vandalizing the paper originals for no real result.
I'm worried that by the time my finances improve (few more years maybe), many of the App Notes will have vanishingly few intact copies still existing. A pox on people who destroy rare historic print originals to scan them.