Have you checked any of the local shops? Ray's Radiator, right at the Madison Heights/Hazel Park/Warren border always had what we needed, very reasonable, especially if you do it yourself. They've been doing radiator rebuilds since the dawn of time, never ever had a problem with 'em... And if they don't have yours in stock, it's next-day radiator rebuild, they are fast...
I am reminded of when my dad's radiator went on his Scamp, he couldn't get my Reliant started, so he took out the old radiator, and rode down Dequindre, from 13 to 10 mile on my bike carrying the radiator in his right hand...
Off-topic there, but maybe you have some delightful local (AND CHEAP) place around that you don't even know about. I love the smaller places, they've screwed things up a lot less than the major chains... Except AutoZone, which I have no issues with.