Try your grocery store, see if they sell like an 8-pack or whatever of 8-oz plastic soda pop bottles (you get the pop too).
Don't leak, last pretty well, cheap to replace when they go out. Weighs less than an ounce, holds all you want. I use these on longer trips for olive oil and in general for alcohol (fuel).

REI sells little plastic bottles with screw caps, I think in 2, 4, and 8 oz sizes (?). I've used the 4 oz size for olive oil, and around home it's a nice size to carry a little water for a several mile home-based walk. Looks like a miniature booze flask, i.e., fits in a pocket nicely. I'm not sure it's much lighter (or any lighter) than the 8-oz pop bottle. The plastic is thinner on those, but they really do stand up to quite a bit. Bulkier, of course.
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Brian Lewis
http://postholer.com/brianle