We now have most of those rare books?
OK, in terms of 3-D books:
There were only 48 3-D newsstand comics during the 50's boom, plus 2 books that had 1 story in 3-D you needed to get the glasses from elsewhere on. This doesn't count giveaways, which are pretty much the Disney Cheerios ones we can't use or reprints of newsstand books.
There are 12 3-D books of the 48 we can't host here: 2 EC, 2 DC, 2 Atlas, 3 Mighty Mouse, 1 Katy Keene, 1 Sad Sack, and 1 Felix. We also had to remove one story from 3-D Dolly.
There were 3 3-D books that Gerber marked as 8; all 3 are useable here and we now have all 3.
There are 17 books Gerber had tagged as 7's; we can't use all of those and we're missing several. While the three books Gerber had as 8's all seem to be pretty scarce, some of the books he had tagged as 7's are way off base, possibly closer to 5's. Some of them really are that scarce, though.
Overstreet only lists one 3-D book as "scarce", First Christmas, Gerber has that as a 7. I've got a copy and it will be forthcoming fairly soon. The only really hard to find 3-D book I think we'll be missing after that would be Animal Fun; although a few others aren't exactly common that's the only one that looks to me to be a real problem left.
So, yeah. We've got most (but not all) of the harder 3-D books we can use here now either scanned or on the way soon.
Probably more of an answer than you wanted, as you can tell it's a bit of pet project at the moment for me!