TITLE: What out-of-print books would you like to see re-printed?
QUESTION [45 upvotes]: It's excellent news that the LMS are to re-publish Cassels & Fröhlich.  There are many other excellent mathematics books which are just about impossible (or at least very expensive) to get hold of, though this problem seems to be getting a bit better with some texts being printed on demand.

Which book(s) would you most like to see re-published?

A couple of comments:
Perhaps nobody under 30 actually reads real books made from trees any more, but personally I find it more convenient to refer to a paper copy, to the extent that  I will happily buy a copy of something which is available free on-line (like SGA 1 and 2, or Milne's Arithmetic Duality Theorems).
And of course there can be legal issues with re-publishing works - EGA & SGA seem to be a case in point at the moment.
Here are two to start off with:

Manin, Cubic forms
Grothendieck et al., Dix exposés sur la cohomologie des schémas

(not including Cassels & Fröhlich because I picked up a copy on Amazon a couple of years ago :-) )

REPLY [2 votes]: Élie Cartan, Œuvres complètes. See how expensive and rare used copies are.