Zeiss 100/2 Macro as fast portrait lens.

Just wanted to give you other options if you go manual focus, if you can find one you could get the voigtlander 125mm f2.5 but its a little longer. for reference see: http://thepictorial.com/reviews/clash-of-the-titan-macros/

From what I have seen the 105mm dc makes good portraits and is not as contrasty as the Zeiss but that is a matter of preference. There is one lens that could be a cheaper but a good option and that is the manual focus Nikon 105mm f2.5 Ai/Ais if you don't need the macro, in excellent condition at keh.com for $235-310 with free shipping.