Payless is opening its first store-within-a-store, called Payless ShoeSource Express, inside an HEB supermarket in Laredo, Texas. The 700-square-foot store, which stocks women's and children's shoes, is exceeding performance targets, according to the retailer, which rents and operates the space. Payless hopes to roll the concept out to other HEB stores and cut deals with other national and regional grocers. Financial arrangements between San Antonio-based HE Butts, owner of HEB, and Topeka, Kan.-based Payless, were not disclosed.