yes ghost shrimp can be in freshwater tanks. i believe they might only be for fresh water. the ones i get are from that fish place in lancaster,pa. if i remember correctly they are 22 cents a piece. that's the least expensive i've ever found them to be. at petsmart i think they are around 45 cents a piece. they don't need any special care really but you should acclimate them just like you would fish. also when you go to put them in your aquarium make sure to put your hand over the net or they will jump out! and also check the net carefully after you put them in the water. sometimes they get caught and are still in the net. what size tank do you have? you can keep e a few shrimp in a 5, 10 gal. i believe they say 1 shrimp per gal of water. they also can take temperatures that range from 65-80 degrees. good luck!
