Cheaper? Look for a SS cooking pot with the correct diameter. What is the Gatorade bottle's diameter?
That gives me the idea of finding a small jug with the right diameter to fit one of my Ti cooking pots. I've always carried a Nalgene inside a Snow Peak 700, but for my larger kit, a water jug inside my Snow Peak 1400, diameter </=5.75".
I pack a Primus LiTech Trek Pot. A 32 oz Gatorade bottle or a 1L Nalgene bottle fits in with plenty of room to spare.
_________________________
Earth and sky, woods and fields, lakes and rivers, the mountain and the sea, are excellent schoolmasters, and teach some of us more than we can ever learn from books.
John Lubbock