Am on. 4mg/day flomax (tamsulosin). Switching to saw palmetto. Is finest nuitrition 450 (serenoa reopens) (fruit) a good brand to use for this transition?

Ask your pharmacist. Saw palmetto 150 mg and pygeum africanus 100 mg twice daily is an adequate daily dosing. Your pharmacist or herbal therapy provider should provide reliable brands. These chemicals are not fda regulated.
Brands. We don't recommend brands here. Also, unfortunately it's really difficult to find out if a supplement manufacturer is "good" and actually contain the stated ingredients in stated quantities because supplements are not regulated by the fda.