This is something I noticed with some of the Secret Lairs in my collection. A lot of the -rainbow- foils (not 'regular foils') show as the price "N/A" in my collection while the regular versions of the card have a price value.

I noticed it initially with the Final Fantasy Secret Lairs as that's when I started playing again, but it's also the case with the rainbow foils from the Playstation Secret Lairs -- all the rainbows show price as "N/A". It might be because TCGPlayer has a separate URL link for "rainbow foils" for cards vs just toggling the foil checkbox on a listing page, so I'm not sure what's involved in correcting it but noticed this and wanted to mention it.

Hope this helps! :)