A good 550W at $60 is hard to find, and the only brand that would fulfill that would be FSP Group/Fortron/Sparkle. I wouldn’t trust any 550W that can be dropped to $30. The only way you can get a good 550W PSU for $30 is on eBay or in a forum trading section. I haven’t been able to dig up much, but Power-Up seems to be on an avoid list that I found at [H]ard|Forums, and a lot of the brands on that list are already ones that check out as a brand to avoid.