look on joshsfrogs.com at the fruit fly kits. You can get kits that come with everything you need

Cups with lids
media
excelsior
herptivite
calcium
and flies to start your cultures or feed from

Its recommended you toss out a culture after 4 weeks. Typical practice is to start a culture or two once a week so that you always have flies on hand should one of your cultures happen to crash