You can get reasonable quality ones for under £100 .... both of my replacements are from fleabay .. but quality supplies.
All rads, have a working life or 5-6 years .. 7 if you are lucky .. having the two cores (rad and condenser) so close together means the cores rot .. I've taken one out and watched the core literally disintegrate to dust before my own eyes .. and couldn't see the leak!!!
I got a Nissens Aluminium rad for my 156, lasted far longer than the original Valeo or the replacement Valeo. The Aluminium Nissens one is still in there now, 8-years later (already twice as long as the Valeo lasted...).
It was £120 at the time, bit less now.