I have made several batik tops and have used both batiks and cottons for the backings. My longarm quilter expressed concern with the batik backing, said she had problems in the past with batik as the backing, but the ones she has done for me turned out great. I personally prefer flannel backs for all my quilts, it just makes them so cozy.
My LQS has a deal on the first Saturday of every month - bring in a completed top, receive 30% off any type backing fabric.