Yup. A good PSU is key, and unfortunately, a lot of people don't give much thought to the PSU they buy. They pay attention to the advertised wattage, which really doesn't mean much these days. People still assume that bigger numbers mean it's better. I have to shake my head at people that are willing to drop $500 on their CPU, but want to use some crumming $25 600W power supply to save money. Having a $40 350W PSU is almost guaranteed to run circles around the cheapo 600W, it's not even funny.
Basically, getting a good PSU is the same thing as putting premium gas in your Ferrari...if you want the thing to run at it's best, you will get the good stuff. You will pay if you go with the cheap PSU, or with the Ferrari, the cheap gas.
True, there is something to be said on price vs performance, but these need to be kept in check. You can find a good product for a decent price or cut corners elsewhere, but you don't want to go cheap on a part that can seriously affect your system's stability, and you're a fool if you do.