I also recall PE's comments on the subject on this site, but I don't have an exact pointer. Given the cost of real Photo Flo (or other brands' equivalent products), I don't see much point in using anything else except in unusual circumstances (say, you've run out).

I have seen posts from people who use distilled water with no wetting agent at all as the final rinse. I've never tried this myself, though, so I can't comment on how well it works from personal experience.