I have recently bought a new lens, on ebay, for around 100€, the famous Vivitar 100F3.5 Macro
They are quite right when they say it’s plasticky, noisy, and light; but I have to say that it autofocuses quite well on my Sony Alpha A55. And the performance… look for yourself. Click for bigger size.
With manual focus, 1:1 with the matched adaptor; focusing is not easy (I ended up fixing the lens to 1:1 and micro-adjusting the camera position with a cheap focusing rack on a tripod).
Autofocus, handheld, 1:2 (approx).
Nice, eh? What I really like are the colors that this little lens is able to show…