If we are talking about out of stock/print book, I usually find them on Ebay, and I usually wait patiently that one arises at a descent starting price. For a European guy like myself, the trick sometimes is to try searching directly from other countries site (.com, .co.uk, .fr, .de etc..).
For new and forthcoming book, as I live in Europe (France), actually the best places to buy these beautiful AND fragile books are in my opinion the Forbidden Planet stores: Forbidden Planet.co.uk and Forbidden Planet.com (these are separate entities), as well as Archonia.com (a Netherlands based company). Prices are sometimes a bit higher than Amazon but these stores know how to do a proper packaging for these kind of unusual books (in term of size and weight). Of course the customer service of amazon (.com, .fr or else) is unbeatable, but it doesn't guarantee that the replaced order will have a better packaging than the precedent (I speak from experience). And as FP and Archonia sites are based in Europe, you won't have to deal with additional custom fees.
Books prices are more attractive at FP.co.uk, but shipping costs are much lower at Archonia.com (they use the Kiala network) so all in all, you will end up paying the same total amount.
Notice that with FP.co.uk shipping costs are calculated upon shipment and they normally asked you by mail if you are ok with the shipping costs before sending the book(s), if the fee is consequent. Oddly they don't wait for your response to charge your credit card for the book(s) only, but in case you decide to cancel your order because you think shipping charges are too high, refund is automatic. They also do monthly combined shipments (i.e. they can keep books already in stock until the end of each month), you just have to ask them by their contact mail form. To France they use 2-3 days DHL delivery with a tracking number.
There are some pictures of how Amazon and FP handles packaging on this French forum topics:
- Artist Edition (page 12)
- Belles éditions VO (pages 6 and 7)
- Amazon se fiche du monde? (pages 18)
Now, some low print variant/signed/remarqued editions are often not available for pre-order or order through the distributors listed above.
For the time being, IDW Artist's Editions (or IDW limited) as well as Graphitti Designs Gallery Editions variant/signed/remarqued editions are only available through their respective web stores (IDW web store, IDW Limited, Graphitti Designs web store), and thus at full cover price.
It seems that Dark Horse signed Curator's/Gallery Editions are available through the distributors listed above (with their respective discount).
In USA and Canada, I think that many serious collectors rely on InStockTrade (aka IST), Cheap Graphic Novels (aka CGN), or Tales of Wonder (aka TOW). I haven't tried them myself but they have good reputation in term of price and packaging quality.
For general purpose on omnibus, deluxe hardcover etc.. (where to buy, what is what) don't hesitate to check these invaluable threads on CBR board about Collected Edition:
- an introduction to collected editions
- general omnibus and hardcover discussion (the first page has updated information)
And specifically for Artist's Editions type books, and can't recommend enough these three links
- Comic Book Daily's Artist's Editions exhaustive index (check out also the site itself, it's excellent!)
- Artist's Editions discussion thread on MarvelMasterWorksFanSite
- pour les lecteurs français, le fil de discussion dédié sur le forum BDGest