Is it possible this is just a bit of PR spin by Wallmart to position themselves as being cheaper than Amazon or have I been working in marketing for too long?
Remember, FBA charges you money to use it beyond the cut Amazon seller already pay to sell in the platform.
(Neat thing: a friend of mine was one of the devs on the Amazon FBA seller app that lets you scan barcodes at other stores and see how much you'll make selling it on Amazon)