PGI (Palm Gaming) sold their greek key mold (reverse-L version) china clay chips with or without custom high-quality labels, plus they were also available from their retailers (one of which who branded their version as 'Great Wall' or Wallsons).
Because PGI controlled the raw materials used in their chips, the quality and play characteristics tended to be better and more consistent than that found in other mass-produced china clays A 30c to 35c per chip price in today's market is about right for your set, which was likely produced around 12-13 years ago. You certainly could have done a lot worse buying without samples or some in-depth market knowledge, so well-done there.
For example, the Progen-80 china clay chips mentioned earlier (not yours) were made using a similarly-colored but inferior greek key mold (reverse-J version, with an extra hook) with far worse quality control, using recycled materials and typically affixed with low-quality labels. They tend to sell in the 15c-20c per chip range, and mixing Progen-80 chips with your PGI chips would be a mistake, imo.
As
@AWenger noted above, the spot pattern and color configurations of PGI's china clay chips (and seveal other manufacturers' chips, too) were 'copied' from several popular Paulson home market chip lines that were initially produced a few years earlier (Top Hat & Cane Classics, Pharaoh's Club & Casino, etc.), circa 2004-2005.
Enjoy your new set!