One of the best, if not the best budget power supplies is now $30 after mail-in rebate till the end of the month. It is made for Antec by Seasonic, which is widely regarded as the best PSU manufacturer overall.
To give you an idea of what it can do: it powered my main rig for about 3 years, which consists of a 1st generation Core i7 930 overclocked to 4.1GHz (a huge power hog), 12GBs of RAM, two SSDs in RAID 0, a 1TB platter and two SLIed GTX 460s that draw about 150W apiece. It now serves as my spare.