I currently don't keep crickets over a long period of time but I plan to use because I get tired of the .11 cent crickets at PetSmart. Could a moistened cotton ball be an alternative to water crystals?
the main thing is you don't want a pool of water that will allow crix to drown in. also the cottonballs will hold bacteria but it should be an acceptable alternative for water crystals. although the water crystals will stay hydrated for a longer time.
Cotton balls, paper towels will work just fine. You will need to replace them daily (maybe twice a day if you have many crickets) They will get very nasty fast and as was mentioned, become a huge bacteria playground.