Usually a company or school will purchase a new computer via lease for a period of time, at lease end, having a lot of use life remaining in the unit, the computer is turned in, tested, cleaned and resold as a certified pre-owned computer and you can pick up a decent unit for only a couple hundred dollars.
The one we are going to be looking at here is the HP Elite 8300 desktop PC. This is a pretty compact unit, on the front we get an optical drive, four USB 2.0's, a headphone/microphone combo jack and a standard headphone jack. Then moving to the back it has Ethernet, another two USB 2.0's, four USB 3.0's, a display port, Serial port, VGA, two PS2 ports, and dedicated microphone in, as well as audio out.
At the top of the unit there's also a ring to padlock the case shut. The cool thing about this unit is it’s easy to upgrade. By pulling this handle you get access to everything inside and it’s all laid out in a compact yet easy to reach manner.
The specs might not be top of the line these days, and wouldn't be ideal if you're wanting a computer for gaming, because of the form factor you would need to find a low profile graphics card. But depending on your use case this could be all you need. That Intel i5 processor will be great for any word processing, business or home office use. And there's a few RAM slots free if you feel the need to expand on the 4GBs it comes with.
Check out PB's range of off-lease computers either in store or online.