Not to hijack this thread, but a couple of comments:
I don't think that '86-'87 GN center caps are interchangable with '86-'87 T-Type & Turbo-T center caps, but I could be in error.
Those center caps seem pricey to you because you are evidently used to standard & repro GN caps & such, which are still being currently manufactured extremely reasonable.
Pricey is $300 & up for 4 standard NOS '86-'87 center caps which are no longer in production, or $300 & up for 2 GN headlight bezels, $400 & up for 2 chrome headlight bezels, $500 for a '86-'87 NOS hood liner, or $400 & up for a NOS MAF. Now those are pricey. IMHO, these caps are very reasonably priced for what you get.