Cheapest fan unit I could get was from Dronsfields, its the VEMO make like I have which failed after 4000 miles. Price was £300 plus vat.
problem is it is a sod to take out the old unit, removing atf and water hoses etc.
Took out the fan motor took it down to my local rewind shop. They stripped it and it was the shaft that had worn inside the bearing next to the pully.
Be very careful when you remove the motor the fan/pully is bakelite and if you drop it like me it breaks.
It takes about 20 minutes to remove the motor and same to replace, it is fiddly getting the ribbed belt back on but not impossible.
In all it cost me about £100 and the car was only off the road for 1/2 day.
If it is the fan bearing the fan can be removed on its own 3 ph screws and the bearing replaced, again none of this requires removal of the fan housing.
Good Luck