I've never bought pre-made bamboo backings, only made them by hand, but from what i understand, you'd still have a lot of work to do with them anyway. The trick to bamboo backings (which i learned from Pat B) is to draw the bow shape on the bamboo, cut it to the lines, and then thin the bamboo to a knife edge, end to end. This prevents the backing from being too thick at the tips. With pre-made backings...i don't know.
Hickory backing strip...can't go wrong...doesn't matter what shape your bow is, the thing will be uniform thickness throughout anyways.
If you have a tablesaw and beltsander, you might consider buying hickory lumber and making the backing strips yourself. For the price of one pre-made strip, you can buy a board 6 feet long, 1 inch thick, and at least 6 inches wide, meaning that you could make 12 or so backing strips for yourself.
Have a good time with your bow, buddy!
