I'll cling to my GX stuff for life. Especially seeing as they're NOS.
I don't think these prices can be considered at all as I simply cannot see how anyone of the members can even afford them now. Sad story really.
Don't consider it as a bench-mark, consider the GX Exhaust manifolds as extinct. Everybody will sell out now. I remember when Mike sold his one (or two) last year and that was for a fortune, I couldn't even contend with the figures he was offered. And I thought those figures were high but look at the prices above! Mind-blowing.