Gary at Williams Arms can order you one for $495. I threw out my bill when I bought mine.
The Colt Second Generation Walker that I bought in the States is a rare Walker made between May and September of 1981. They made only 245 of them. Mine is coming with an oak case (but no accessories). I have the powder flask, I only need the nipple wrench and bullet mold (but I don't want an Italian-stamped copy).
Happy hunting!
Cheers,
Bill