You can get a brand new rad from ebay for £35 plus delivery, from a company called cooltek I think.
Fairly easy to replace unless you have aircon, then the issue is getting through the lower front grille to the two lower aircon condenser mounting bolts (the condenser needs to be unbolted from the front of the rad). I popped the clips on the grille (which is also held securely by the front fog light trims) and reassembled the grill to the bumper with a light dab of silicon at each clip point as I was not going to take the bumper off to fit the silly clips again!! basic run-down as follows :-
1. remove air inlet duct from filter to MAF.
2. remove lower hose at engine end and drain into container, then remove upper hose.
3. unbolt fan assembly (qty 4 8mm headed hex bolts), don't disconnect wiring, flip it up and back over top of battery out of the road.
4. unclip and remove lower hose, catch remaining fluid.
5. remove front upper grilles and remove shroud and aircon condenser upper bolts.
6. remove fog light trims and prise lower grille from clips
7. remove centre top bolt at rad and tilt rad rearwards, then lift out.
A bit of a fiddle getting the shroud to stay where you want it whilst you get the new rad to sit down into it's two lower rubbers, but simple enough with patience.
I should also point out that there are two relatively inaccessible screws at the base of the shroud, going into the bottom of the rad, but these had corroded away completely on mine. I managed to get new ones to go into the new rad, however, although they aren't essential!
Hope this helps.....