They (Walmart Labs) do pay pretty decently. In all honesty, the solution may just be a total rebranding of Walmart's online platform and development team. If it were called "Bazaar" or something equally sexy, they could probably attract not only more talent, but more shoppers in the millenial demographic.
If their upper management has any smarts, they have to know all the connotations and baggage that go along with the name Walmart. I don't think it's a brand they can hang on to forever.