and in addition to the homeopathic i posted above, is the following high quality supplement from a VERY high quality company :
http://www.lef.org/Vitamins-Supplements/Item01209/Water-Soluble-Pumpkin-Seed-...
http://www.lef.org/Vitamins-Supplements/Item01408/Super-Saw-Palmetto-Nettle-R...
Have you looked into Super Beta Prostate supplement. Reviews claim that it helps increase urine flow and improve prostate health. It contains beta-sitosterol as a key ingredient but has over a dozen other nutrients in it as well.