Dont bother with Petco ( except in emergencies ) as they sell only vials. You can buy the culture material ( media, containers, etc ) online for pretty cheap. Go to the sponsors on dendroboard. This way you can make larger cultures and keep two or three going at a time in case of crashes (they are prone to it). If you're in my area, I could always set you up with one to get you started. Its very easy - mix equal parts of media ( which is mostly potato flakes, baby food powder and anti-fungal stuff) with warm water ( distilled preferably ), sprinkle little brewer's yeast on top and let it solidify. Add some kind of material for the flies to crawl around on ( mesh, cofee filters, shredded paper ) and presto - within a couple of weeks you have a teeming fruit fly culture. Now make sure not to pull one of my moves - wild flies somehow got to my culture ( if the material on top is thin enough, they can mate through it ) and when I didnt realize there was a crack in the cup, and lots of family was over for that thanksgiving - lets say I almost added to the homeless statistics in this country.