If you're getting the incompatible thing then the PS version needs to be newer than what you have. I have plain old CS (number 1) and don't have too many problems with brushes from newer versions (in fact, I don't think that I've ever had a problem getting a CS3 brush to work in my CS) but I had a heck of a time when I was still on 7 trying to get CS brushes to work. So you will need to update but is the price worth it to you? Alternatively, you could just take an image, crop it accordingly, and click "edit - define brush preset" and make your own brushes from the given image. It's a lot of work but it's far cheaper than upgrading.