Recoring your exisiting radiator could be an option too....I just checked in Australia. A recore of the radiator (you only need the top, bottom and side bits...they put a new middle bit in for around $200.

I'm not sure what a brand new 1200 rad is in $AUS - but I think it would be difficult to get a new one for that price.

A 2nd hand one still needs to be pressure tested, checked for blocks that in Oz might cost $10.....to get it soaked overnight to unblock it, maybe an acid wash too around $50.

Convert all that into US....and maybe it relates.