The best and cheap gasket supplier is yourself!
I made my own gasket using a roll of gasket paper that I purchase from a large auto-part shop (you have to select your own paper thickness).
How to made a gasket: Take a piece of gasket paper and lay it on the flange of the manifold. Then, gently tap around the inlet bore and outside of the flange with a small ball pein hammer to cut it. Obviously, you have to remove the carb studs (if any) before to do it. For the fixing holes, you can use a large 1/2" iron ball to punch it.
