Did a little more digging, and found replacement lids on the Kid Basix website. At $2.99/lid, I think that's an acceptable amount to invest, to keep using the stainless steel water bottles.
These 12 oz. water bottles are perfect for my kids' lunches. I rinse them out each day upon their return home with soap and water, and they're ready for the next day's use.
However, I've noticed a fair amount of wear at the pull-up nozzle (one child chews on theirs, others' have food stuck at the shaft on the inside), and I cannot take apart the lid/nozzle to properly clean. Also had a small issue with mold (??) in one bottle, that a light cleaning w/bleach and a bottle brush cleared up. Finally, one child demonstrated that their lid leaks at the neck/silicone ring.
I *do* like these bottles and would like to keep using them - are there replacement caps available?