Look over by the pharmacy, kind of by the suppliments. It will be about waist level (if it is in the same place - all Wally worlds can be different you know) in a clear bottle with a white label. It will have blue lettering with a sort of pink area surrounding it with 'HUMCO' in large, double lined letters and a tiny 'USP' in the upper right corner.
It took me some time to find it also - but they definitely have it, and somebody should know, but most of them probably won't. lol - Just take your time and look and you'll find it. Most likely someone in the pharmacy can help you if you have trouble.
Take care,
- Hap