You could try the old trick of using a piece of stretched nylon stockings over the lens. I think it was the common technique for female "portraits" (movie) in the old days. Bogart was portrayed from below, no stockings, probably harsher light and Bergman was portrayed from above, with piece of stockings in front of the lens, probably softer light. I don't know if it is a solution which satisfies you, but cheap it is.

An expensive alternative is the Minolta Rokkor 85/2.8 Varifocus lens, which has a ring allowing the photographer to set the desired degree of spherical aberration. (bottom of page)