I managed to snag four for about the price of a store-bought pouch each on mamabargains.com, thanks to a mama in my due date group. And at 6oz capacity, I have a pretty happy little belly.
So far, I've only used it for purees for Miss Em (9m), but I plan on expanding to smoothies and yogurts for Miss O(3yr) as well. The sport size would be great for her. Miss Em does well with the pouch all by herself, throwing it across the room when she's finished...and it only makes a little mess along the way ;] The caps/spouts of these, the store bought pre-filled pouches, and other reusable pouches seem pretty universal. Yummi Pouch makes a little spoon attachment, but I've also seen a silicon spout extender from other brands that would be handy for self feeding.
The pouches are easy to clean with a bottle brush, or as previously mentioned, they are dishwasher safe. Be sure to dry thoroughly to prevent mildew. I've had no issues at all with the zip seal, it passed the squeeze test no problem! The opening is big enough that they are pretty easy to fill, also.
I love these pouches and would absolutely recommend them to those using purees in any capacity.
You can purchase the classic set on the Yummi Pouch website 6 for $14.99. They also come in sport size (10oz) and mini (2.5oz), as well as many accessories.