One of the worst aspects of DJing is gear — buying it, storing it and lugging it. A minimal setup for a backyard party, including two self-powered speakers, turntables and a mixer, will run you more than $2,000 new. And that's not counting a laptop and a pickup to haul the stuff. We discovered Cosmos a few years ago while helping to organize entertainment for a company party. The prices can't be beat. Technics turntables rent for $25 a day. Self-powered, 15-inch JBL Eon speakers (which retail for about $1,500) go for $55 per day. Top-of-the-line Rane DJ mixers can be had for $75 a day. And if you're local, they'll set it all up for you and come pick up the gear for $200 to $300, depending on how much gear is involved. Cosmos serves everyone, from house-party faithfuls to major-production venues. It provides sound and lighting for big-name concerts, but somehow the technicians have time to explain how to set up the XLR cables on those JBLs. They also sell and repair gear and recently opened a Cosmos DJ Academy for hopefuls who want to learn how to spin records — and lug stuff around. 6060 Hollywood Blvd., Hlywd. (323) 957-1200, cosmos-sound.com.