I bought some of these from REI Admittedly, I originally bought them to fill with soap/shampoo for travelling and my gym bag. Liked them so much I used the extras I had (bought two 3 packs) to put condiments (ketchup and other sauces) to bring to work and also ended up using one for gels since I had one last one to spare. Only drawback is the flip cap for riding isn't as convenient as regular ones like the Hammer flasks. But, they are pretty quality and mine have are still going strong after several years.
They seem more expensive than I remember because I definitely didn't pay as much as they are listed now.