Daphnia and other live foods

I have looked all over for Daphnia. I have gone to ponds, streams and vernal pools all over my state (VT) collecting water and dip netting with a fine mesh net. I have collected all sorts of creepy critters, but not so sure about Daphnia. I had one container that looked like it had some daphnia in it, but then they all disappeared.
Where can I find Daphnia, or how can I create a culture of them?
I have tons of Psychlops, some scuds (although I seem to kill them off faster than they reproduce), a few water boatmen, some small shiny brown and gold beetles that swim in a similar fashion to water boatmen, mosquito larvae... but no daphnia.
I am keeping several 5 gallon containers of swampy water with all these critters out side -anyone have any advice on how to collect them without collecting the swamp scudge from the buckets?
Thanks!

I have purchased from these guys in the past. http://www.dallasdis...com/daphnia.htm I really like the Daphnia Magna, they are large enough that even larger sunfish will eat the adults, and their young are good for smaller fish.

+1 for dallas discus

I have purchased from these guys in the past. http://www.dallasdis...com/daphnia.htm I really like the Daphnia Magna, they are large enough that even larger sunfish will eat the adults, and their young are good for smaller fish.

Cool, affordable prices! Thanks!