I had the same problem on my B16A2 radiator (top tank busted).

Got quoted $180 to replace the top tank (when supplying them with the bare radiator - out of car). Bought a 'cheap' alloy radiator - lasted for about 6 months then started leaking out of the fins.

Removed the 'cheap' alloy p.o.s radiator and fitted an aftermarket OEM equivalent replacement (plastic tanks) for $150. Still going strong!

Moral of the story - you get what you pay for. Generally when it sounds too good to be true it usually is... Especially when it's an eBay item!