The one I posted on the first page cost ME about $700.00, and the radiator shop guy (age-old and highly recommended to me by different sources, located in downtown Toledo) stressed the fact that what he built had a retail value >$1000.00 (I put 15% on my cost for making the couple of trips to drop off/pick up). Most of the other jobs in his shop would barely fit through your front door__industrial stationary and marine engines primarily, with automotive restoration jobs fewer and fewer.
That core matrix is fully four (4) rows deep, and with the highest available numbers of fins per inch; I think it holds close to 1-1/2 gallons more than the stock one I took in there. This essentially replicates the radiator I had made for my car about thirty-five (>35!) years ago, and still keeping my car in the 170-190* range.
Point is, $600.00 for the radiator that I described does not seem out of line. I'd be curious to know what the (core) specification of the Moss replacement is, as I've seen two (2) different cores in Healey 6-cyl models; the 3-2-3 rows staggered (mine) and also an original BJ8 with just a 2-row core. As an example, that 2-row core was half as thick as the bottom tank, and my replacement core is every bit as fat as the tank__the fins possibly protruding beyond it.