new fan, possibly performance?

[How15]

hey guys, my clio is still slightly overheating, and after swapping the sensor, the relays, pulling the wire out the loom to check, and cleaning all the earths, i've decided it must be the fan itself not working correctly.
does anyone know how much a new fan for a mk2 ph1 1.4 with a/c costs, and where to buy one from? is it the same as any other models, and could it be worth upgrading to a performance effort? any sugestions?
howie

 

[Mark One]

yes, but have you changed the coolant itself yet?

 

[How15]

i've not flushed it and fully changed it, but surely just the actually liquid wouldn't cause it to overheat? unless there was a blockage or air in the system, but the pipes are hot and i've bled it. it's always had a good mix of water and coolant.
the fan comes on if you disconnect the sensor, and come on briefly if the needle gets about 3/4 up 2 return it to half, but i've had the car over 3 yrs and driven 40k, i know the needle is always steady at below half, plus the fan never comes on when the car is idling or after a long journey anymore, so it cools really slowly. it always used to remain on and would be cold once i'd return to it. after changing everything else i've come to the fan conclusion.