I personally do not agree with your assessment of the print quality of the New Millennium edition of FLP, and though I do not have a copy of the 1966 edition on hand with which to compare it, I do have a copy of the Commemorative Edition, which was printed from the same plates as the 1966 edition, by the same publisher. I measured the size of the inside margins in that edition and in the New Millennium edition: they are the same. Perhaps they appear wider in your 1966 edition because it is older, the spine is more relaxed and the pages lay flatter. I don't know. But in any case, I don't agree with you, and given the low return rates, it appears most people who buy the New Millennium Edition are satisfied with it.
With regard to your advice to "acquire one of the older versions in good condition and deal with the errata online": there have been ~1500 corrections made in the New Millennium edition, which would be a a lot of correcting for people to "deal with," not to mention the improvements made to the figures, the expansion and unification of the indexes, and the addition of a symbol table to all three volumes.
vanhees71: You seem overly ready to advise without having inspected these books yourself. How do you know you would agree with smodak?