Brad at Alfa Ricambi will sell you a new one for about $100, maybe less. Got one from him last year. Some fettling needed with the cable. If Richard has one with a functional cable setup, go ahead. These thing never wear.
I don't see one on there now either. This was a little while ago. You may have to dig deeper. However if you can't find one I believe that I have a good used one with a new cable that I might let go of.
They also still make the heel-toe kit, which I will be getting for my GTV. Not being able to heel-toe in an old car is an unbearable situation for me, as it is one way to make old gearboxes last forever.