Hmmm...*strokes imaginary Nicodemus beard*
...In all seriousness, I have given this subject a lot of thought. I have several ideas, each appropriate to different potential eventualities leading up to/following Ghost of a Tale's release: I present to you my three hypothetical Amazon product listings for Ghost of a Tale's different editions (again, maybe only one out of these three ends up being possible, but the exercise may yield some ideas nonetheless!)
Ghost of a Tale: The Green Flame Edition - Premium Edition limited to 500 copies - $329USD
'For the truly determined Periclavian collector comes the Premium 'Green Flame' Edition of 'Ghost of a Tale', absolutely brimming with ultra-limited DLC and collectable content.'
Included in this edition are:
~ A Deluxe copy of Jeremiah Pena's hauntingly beautiful and immersive Soundtrack to the game;
~ A hand-numbered highly detailed 7" 'Tilo & The Ancients' diorama-figure of all of the world's different races, including a Frog of Vaelia, a Badger of Balahdon, a Hawk of Halenvir and a Myghlar Magpie;
~ An exclusive 'Tilo's Quest' Lithograph, painted and signed by creator Lionel Gallat;
~ Faux-wood and leatherbook casing for the game, complete with twine sealing strap:
~ Assorted stickers and woven badges bearing the Crests of all of the kingdom's animal races;
~ A 120 page 'Tilo's Sketch-Journal' faux-leather bound Art & Lore Book, featuring sketches, history and a section devoted to behind-the-scenes information, renders and more - with a foreward written by Lionel Gallat;
~ DLC skins for Tilo inspired by all of Ghost of a Tale's inspirations, including 'Brisby's Tattered Cape';
~ A miniature wooden candle-and-holder, made using one of the in-game models, with ignitable wick;
~ and finally, a one-of-a-kind 'Perennial Supporter' water-colour-tinted T-shirt, made in the style of Don Bluth & John Bauer!
Ghost of a Tale: The Asper Edition - Collector's Edition limited to 1500 copies - $229USD
'for the passionate and enduring Ghost of a Tale supporter comes the 'Asper' Edition, made to a strictly limited run of 1500 copies, filled with delightfully authentic exclusive content.'
Included in this edition are:
~ An exclusive 'Council of Asper' Member's Medallion, of the race of your choosing;
~ A 7" 'Tilo Hiding From Rat' Statuette, complete with light-up 'flickering candle' display piece;
~ A miniature 'Tilo's Travelling Chest', containing ancient artefacts from his travels and song-paper;
~ A faux-parchment letter of thanks signed by Lionel Gallat;
~ Faux-wood and leatherbook casing for the game, complete with twine sealing strap:
~ Assorted stickers and woven badges bearing the Crests of all of the kingdom's animal races;
~ A limited edition 'Thank-you from the Team' hand-sketched and embossed lithograph!
Ghost of a Tale: The Periclave Edition - Limited Edition limited to 15000 copies- $129USD
'Prepare for a dark and perilous Adventure across the haunted Island of Periclave. In this limited edition are all the wares and sundries you will need to succeed and survive on your Quest.'
Included in this edition are:
~ A Limited edition faux-chipped wood casing for the game;
~ An exclusive 'Tilo's Adventuring Napsack' replica, including semi-scale accurate loaf of bread and ornate letter opener;
~ Assorted stickers bearing the Crests of all of the kingdom's animal races;
~ A special thank-you Ghost of a Tale button pin
~ A parchment scroll depicting 'The War of the Green Flame' bas relief from the game;
~ An exclusive DLC 'Blackwood Rose' Lute for Tilo!
...all editions should also include downloadable Behind-The-Scenes footage and interviews also!
Hope you enjoyed the ideas

Let me know what you think!
References/Inspirations
~ Wrath of the White Witch's Bestiary Tome
~ Dragon Age Inquisition's Inquisitor Edition
~ The Order: 1886's Editions
~ Destiny's Editions