Don't forget that for the paper to stick around you need to add the Create Death Enduring Object, +2 MP... which means your spell to put into the item really is Create Nature 1, Create Death 2, Duration 1 = 4 MP
That depends, just creating sheets of 'paper' should be a by-the-book cost for a wonderous item., MP squared * 1,000 = 4^2 * 1,000 = 16,000 gp. About equivilent to the mid-range for the PHB's medium power Wonderous Items.
{raw materials: 8,000gp xp cost: 4,000 time to craft: 16 days}
Following the rules on Illusions, "The item must have a clear basic effect.." so if you want a Create Nature item to create whatever the bearer wished...that is more like an unlimited charged item.. {Spell lists known * MP} squared * 10,000 = (2 * 4)^2 * 10,000 = 720,000 gp...which is way over the price of a Ring of Three wishes {97,950} but is not limited to only three uses.
{raw materials: 360,000gp xp cost: 18,000 time to craft: 2 years}
I don't think there is a need to inflate prices

Contrary wise, because you have to boost up the Create Nature MP from 0 due to having multiple lists, this item would be capable of creating anything of 100gp or less... a pretty powerful item. If anything, this is underpriced.
Imagine using Create Force instead to create a Ring of Force Armory.. capable of producing any weapon in the PHB with basically a Ghost Touch enhancement...that would be one heck of a boost for a nations army!