I've read, sadly, the growing collectible/antique will be just that, anything and everything handwritten.
Anyways, here is what made me think about this-
Treasure Trove of Unopened 17th-Century Letters
The smell of books in a spray, lotion or candle
I've bought some of Demeter's colognes, they've got some awesome scents!
I was going to say 'but who needs sprays, just have the books themselves', but I suppose you can spray it while reading on your Kindle/Nook or whatevs for ambiance....*sigh*