You can make your own
I made a mount a couple of years ago for a few dollars. You need two good pieces of 1" thick teak, an electric drill with a sharp 1" spade bit and a long bit extension, several good clamps and a vise, and some short 1/4" SS bolts and nuts. I put the two pieces of wood together and bolted them with about 8 (recessed) heads and nuts, then carefully drilled a 1"D horizontal hole from side to side right along the interface between the boards for the top rail, and a perpendicular hole from the middle bottom up to and intersecting the top rail hole. It sounds harder than it is, just be careful to keep the drill bit centered between the boards. Remove the bolts, assemble around the rail, replace the bolts, apply some teak oil, and it'll look and work as good as the store-bought kind. You can custom-fit the angle of the vertical hole if your stern pushpit doesn't have 90 degree T's.