Actually, it depends on what's in it. If its a decent story, I could see 100-200r, but if its just blank or a bunch of nonsense, then it's pretty much worthless...
Alot of people collect well known player signatures I've seen a few of them and many people want to buy rare signatures (admins/ senior staff)
Probably around like 10r, if it is already written and you cant edit it, as well as being blank, there is little to no use for it.
You can't use some you can't use some1's book if they clicked the sign button, once you click that button, nobody can write in it.
Then you need a book and Quill. Written Books are those that have been signed and are no longer editable.
On smp3 they're around the 50r area - although I wouldn't take prices from there, we have no economy. On smp1 i've seen them for 20r, but most for 40r. EDIT: We need Spenser6 here again. Just to make sure you get pony'd.