ATHENS, Greece — In these disastrous economic times, opening a store on tony Voukourestiou Street next to global luxury brands such as Dior and Prada is a goal many Greek fashion designers can only dream about. But despite the crippling financial crisis that has been plaguing Greece for the past six years, 35-year-old Penny Vomva opened a storefront for her designer clothing and accessories company, RIEN, on the boutique-lined thoroughfare last month. Ms. Vomva is delighted, but she also is concerned about the shifting fortunes of the Greek economy. “My line of handmade leather bags costs 180 euros to 450...