Ebay and patience can get you a 135mm enlarging lens for pretty close to dirt cheap. About a month ago I got a el nikkor 135mm in its box and allegedly new, for $55. While I have my doubts about the brand new claim, it is flawless as far as I can see. Stay patient, and don't forget to look for misspellings, and miscategorizations on ebay.
150mm lenses seem to be a bit more still.