I also vote for monoprice.com. I bought FireWire cables for 8$ there while they were priced at 70$ at Staples. Gold plated USB cables, 1,50$ for 10 feet. You can't beat the prices, and the quality is top notch. Their iPhone charger works perfectly, and at about 3$, you can't beat the price.
Okay I'm being overenthusiastic about monoprice, but to answer your question, no, Monster cables are not better. Copper is copper.