i'm not really into monitors, but hz should be your main focus (ms as well, but normally it's always pretty low), according to 'Zouzu', samsung 2233rz is the cheapest one.
let me get this straight.
if you want a 120hz one you have to spend a bit more money on the samsung 2233rz, which is the cheapest 120hz one. one of the best 75hz ones is the benq rl2240h which has 2ms and black equalizer and its only about 130 euros! thats an awesome price