I've never heard of Pied Piper Stores, not surprising as I didn't grow up in California in the 1970s. No doubt they were one of the many "Mom and Pop" toy store chains that at one point dotted our landscape.
One thing i do know is that Pied Piper stores had a pretty grasp of what was popular in 1975, The pages are brimming with the hottest toys of what was a great year. The Six Million Dollar man is present, as is Evel Knievel and more Mego 8" action figures than you can shake a stick at.