I have never seen any Guitar Centers carry Behringer monitors. They could order them for you, but I doubt you'll find any on demo. Other pro-audio stores might have them on display.
If you haven't figure it out, GC stores are generally prone to carry stock on hand that will maximize their profitability. The Behringer monitors will eat alive or at least match products they'd like to move that cost many times more.
People generally shy away from buying speakers via mail order due to the obvious difficulty with live demos. Of course in-store demos are inherently flawed because speaker sound quality is strongly influenced by the listening room and nobody has or even wants the same listening room as a store.