Quick history...
The spotted chips with no bird came out in 2004 and were updated to the spotted bird in 2010. The spotted birds were replaced in 2011 with solid blue with birds. The spotted chips have not been produced for the casino for 13 years. Any that you find in the racks are like unicorns now. Also, the spotted with birds are by far the harder chips to get since they were only produced for the casino in 2010.
For pricing, I have seen them go from $6 to $10+ per chip depending on if they have birds or not along with what condition they are in.