How much do you think a signed copy of Katamari Damacy is worth (signed and illustration by keita takahashi GDC 2005) and a company brochure for grasshopper by Suda51 himself?
not just signed...but it also has an added illustration from keita (similar to the doddles he made during his GDC lecture). I don't intend to sell them, I just wanted to get an idea of how much they could be worth.
You'd have to find someone willing to pay money for it.
I don't know, if you think Katamari is going to become some long-running, significant series, I'd recommend sitting on that as long as you can hold out. It'll be a lot more significant then.