FYI amateur series don't enforce seat certification. The CASC rules regarding seats are along the lines of "must be securely fastened". They only check belts and to a lesser extent, helmets. Hound the CASC forum and kijiji, also check the BFC track FS. eg:
I have a basic Sparco seat that I used for track days, I am probably going to sell it. I am not sure what the model is (may be a sprint) but it is in good shape, bottom mounts. PM if you are interested, can send pics next week.