Umm, talent...can I have that?
If not, I guess a room dedicated to calligraphy and crafty type things. Oh, and a couple of boxes of dream nibs.
Talent may be limited by its rarity.
(But I like the answer and wish to appropriate it for myself)
Otherwise, really good, antique paper. I'm talking the fine stuff from the 19th-century. Like some of the Royal Irish Linen paper they made from scraps from the Irish linen mills I see advertised in the old journals. May also be limited by rarity.
How about a beautiful old writing desk with lots of pigeon holes, and a wafer-thin
mint OLED light screen carefully inlaid into the surface with a yielding, transparent surface on top of the screen? Turn off the light, and it looks like a writing desk with a writing surface. Turn it on and it's a light box built into a massive old writing desk. (don't forget the pigeon holes, and a secret compartment or two). Not rare, just very expensive.
Oh, and room to hold the massive writing desk, but I guess that's two things. Oh, what do I need a dining table for?
I'm sure my wife would go along with that. Don't you?
Andrew