Hi
I'm looking forward to build $200 Pc, mainly use for browsing and watching youtube
No need to be tiny pc, regular size one is ok
PC only, no need to include monitor, keyboard, os or speaker
Your best bet is a used Sandybridge i5 or Ivybridge i5. You can find refirb ones for cheap. Or other quad core.
The AMD apu's compromise cpu speed a bit but have a much better gpu.
if your in the big city or near a unv see if there it dept is tossing out any old pc. a lot of time look at your local classifids and you can find comp it that are dumping 10 or 20 old pc for parts.