Don't have pricing, but have a look at this thread:
FYI, ccohn2000 is one of my dive buddies. She's the one with the glue-on roller.
FWIW, I think it may be easiest to simply make one, especially if you have a friend who does sheet metal (or are handy with fiberglass). Basically, Carol's is a low profile box, contoured on the bottom to match the tube curvature, base flared outwards, and is glued on with multiple layers of hypalon (I think there's a layer to fit around the box edge, then a layer that isolates the box from the tubes. End result is that the edge of the box is sandwiched between the hypalon layers. I think.) The roller itself bolts to the box part.