Buy used rather than new. This applies to cars, furniture, electronics, you name it. Not always practical or optimal but a lot of the time, it is. And when you're buying used, you can haggle.
Corollary: Dave Ramsey's observation that Cash is King. It's less true now that commercial sellers (car dealers, big appliances, etc) often make money on selling you the financing, but few sellers will forego a sale just because they're not getting a commission on the financing.