Can I legally download music from a website?

I don't know what site it is, because you did not say. If they are selling music, it would be hard for it to get much cheaper than I tunes which is about a dollar a song. However, there is plenty of FREE music to download on the internet, on sites such as the Amoeba Record Store site, a daily tune on KCRW, lots of albums free or for a tip to the musicians on Noise Trade and Tweet for a Track, and on and on.

If the website owns the copyright in the music, licenses the music from the owner, or if the site has the music produced as a "work for hire," it can probably set the price of the music at whatever level it chooses. Perhaps it can undercut iTunes because it has lower overhead expenses. However if there are already public reports questioning the validity of the site, it's wise to stay away from it.