There aren't as many made as there are of other chips. I bought up "all" of the NCV chips from a closed casino. (which turned out to be all but about 500 or 600 total, of the $5s, $25s and $100)

There were less than 40 of the $1,000 and less than 80 of the $500's. Another casino I found under 40 of the $1,000 but somene else may have gotten 20.

Point being that many times the casino will order one box of 100 or maybe less of the $1,000 and $500 chips, because they don't need to have many of them.