Instead of buying some bottles of Gatorade (or other brand), buy a big package of the powdered mix. You've just saved enough extra money to splurge up to $5 on a real water bottle that will last longer, be easier to drink out of due to a softer plastic used in the top, and -- most importantly -- be much easier to make clean and make sanitary due to a larger opening.
While I have lost several water bottles (or usually just the tops), I have never worn one out and have never paid over $5 for one and it's typically been less than $3.