I don't have an Orr rookie, but there are a lot of them out there. You really need to be specific as to what grade range you are looking for. The price between a 5 or 6 can vary quite a bit! If you can give more detail, you will have a better chance of finding what you are looking for. Are you more concerned with price or condition?
A lot of people on this forum collect Bobby Orr, and some collect his cards more than any others. Also, there are lots of his rookies on eBay, so you won't have any trouble finding a specific grade with a little bit of patience.
There are others on this forum who can tell you exactly how much you should pay for each grade. That way you won't overpay!