Problem is OcUK doesn't sell a cheap case+psu combo.
You can get a cheap case ( MS-Tech or so) + 430w PSU ( a bit enthusiastic spec, it's probably 300 ish watts, but more than enough if you don't have a dedicated gpu which draws a lot off the 6 pin plug) for 30 quid...
60 for PSU + case in a sub 200 pc is taking the pee... 30 max for both, MS-Tech LC-10 is absolutely fine for a basic pc with a dual/quad core, a light gpu ( one that manages on the power off the pcie slot), 1 hdd, 1 dvd, etc...
Secondly, definitely go 2nd hand with mobo+cpu+ram, better get a q6600 or so over a new gen Celeron imho.
No reason to go for the expensive new sockets imo. Or expensive cases and psu's.