Sorry, I don't know about La Molina, but if you cannot find anything close, and you want to see the mother-of-all-suitcases-emporium, go downtown (mid-day, avoid the traffic) to the Amazonas gallery. Dozens upon dozens of stores selling only suitcases. Unbelievable.
The area is is a little sketchy nearby, fyi. And if you only want one suitcase, cost/time/benefit you'd be better off paying a higher price close to home...
Unless you want to live the adventure
Location: Jirón Amazonas 478, Cercado de Lima