SnowPeak makes titanium 2-piece (around $30) and 3-piece (around $50) cook sets that fit a Nalgene bottle. This includes a pot, a lid, and for the 3-piece, a cup. I plan to get that (or the cheaper stainless steel one from Campmor) soon.
I bought one of the stainless cups from EMS that fits the Nalgene bottle. This goes in my backpack emergency kit (Nalgene bottle holds survival stuff) - for boiling water. This is not a multi-piece cook kit ... just the cup.
Go to http:/www.ems.com and search for "cup". It costs $7.50