ebay - i bought mine off there 

dont overload the PSU though as they arent very good ones usually, but thses are £50 ish for  a   realy good one! 
 
BUT! {i learnt the hard way!} dont add neons and fans etc... with a crappy PSU as you fry your mother board, PSU and processor costing you lots!
if you find cheap monitors please PM me with the address! thanks!
