The Snow Peak 600 single-wall titanium cup weighs 2.8 ounces and holds 20 ounces for $35; the 450 single wall weighs 2.4 ounces and holds 15 ounces for $30. (I usually use the 750 pot with lid as my entire kitchen, but if I need a second pot, I the 450 cup.) You'd need an aluminum foil lid, of course. I don't believe either cup has measuring marks, but it looks like the rivets visible on the inside are approximately 1/4, 1/2, and 3/4 of the volume.

I really like Snow Peak cookware. The measuring marks in the pot put it a step above MSR, in my opinion. (MSR is good, too. Not sure how prices, weights, and volumes compare.)