LC-B400 ATX Replacement

Hello,

Recently I was called by a friend of mine about a faulty security system, she stated it had worked for the last year but recently stopped working. I drive down, note this is a store security system, not household. Now I get there and go to boot everything up and the PCU won't start. I take it apart and there is about 3 inches of dust covering everything. Cleaned it all out and it starts up but after 10 seconds dies off. I look and realize it was the PSU. I take it out and take it apart to see that it looks like some kind of liquid came in contact and the entire thing blew. The PSU was an LC-B400 ATX, by Power Up. Now I know this is a very crappy PSU but I am not great with the whole PSU replacement thing, I can easily get a same model and hook it back up however I don't want to set them back up with a cheap PSU. My question is what kind of PSU can be used as a replacement?

I have a picture of the specs but am not allowed to post it so here's a small diagram:

AC Input:
Voltage: 115V- 230v-
Current: 10A 6A
Frequency: 60-50Hz

DC Output:
+3.3V +5V +12v -12V +5VSB BLK GRN GRY
28A 30A 20A 0.8A 2A COM PS-ON P.G

The PSU had a 20 Pin power adapter, a seperate square 4 Pin, Four 4 pins and 2 SATA's. Also, I don't want anything too expensive, something that's relatively decent price wise and not too crappy.

Thanks