CDnow.com: Definately, the first place to check for commercial releases at a discount. The top online cd source.
Felch Records: A fine source of rare and collectable classics.
Hard To Find Records : If you can't find that classic or white label here, you won't find it anywhere.
X-Radio.com: Not just a net-radio site but also a great source of dance music for sale.
Music Tool Shop: All the music gear you need at the prices you want.
Musician's Friend: Based on their prices and gear available, they actually are a musician or a dj's friend. No salesman to hassle you.
Release The Pressure: One of the first place to stop when you reach London for new music
MDMA Ltd: Label and distributors; MDMA online has endless tracks to show you that Israel is definately a rising hot spot for club music.
Coolwax.co.uk: An independent record store based in the UK, specialising in Vinyl for DJ's. Since opening they've built a good reputation as a supplier of all genres of dance music.