I bet it is from Crate & Barrel. I have the desk in black. The only color the corner piece comes in is white. Or it was when I bought mine. Check them out, they have quite a few things that can be used for a craft room.
Oops, my mistake.....Pottery Barn not Crate & Barrel.
As far as getting the white top dirty, you could always put glass or plexiglass on top for protection.
I wish they had the corner top in the black color to go with mine.
I think the furniture is from Pottery Barn. I turned one of the bowls over & it still had the PB price tag on it (the price had been removed though). This looks like the Bedford collection. The bottom pieces are sold separately from the tops & the hutch. It comes in white, black & mahogany. I've been thinking about getting the small desk (not pictured) for my spare bedroom.