Currently, you would be luck to find one under $30 on Ebay. Try posting a wanted ad in the Wanted section here.
Unless it is a sentimental thing and you want to fix it and not use it you may want to scrap it and go with another brand. In my experience using this style of MAC ratchet (MR5,XR8 and VR10) are very weak and prone to failure. I have several old Mac ratchets, but they sit in sets and hold the shelf down they are sitting on.