I can't see these coming from the PC8 factory this way -think about it, Nike would have had an entire production line set up with red stitching for the Jumpman embroiding, they would have had to stop the whole production line, change the stitching to blue for this one shoe ...then change it back to red. Also, they would have had a whole batch of red insoles ...& 1 random blue pair?
As you can clearly see from the tag, they are just regular produced X -if they were samples of any kind, one offs, PEs etc. this would be reflected in the tag.
There is a pair of Blue Shadow Xs that were supposedly customised for Nick Anderson & were owned by Carter1203 -it is possible that these are that same pair, but those are known customs.
It sounds to me that whoever is selling them is trying to make them out to be a bit more special than they really are ...(obviously to get a better price)
Don't get me wrong, they are a nice authentic pair of OG Xs & it is admitedly a good, clean custom job. & they are rare just because no-one else has a pair like that ...just don't be fooled into thinking they are some sort of super rare samples that Nike released that way.