In this post it's noted that that the price for prize chests will go up 50% after 1000 minor chests, 500 major chests or 100 ultimate chests.
These are the same numbers that were noted when I first read about these chests coming out in the town hall summary.
I was able to purchase 10 ultimate chests and the price has already jumped 50%
The Glint shop is currently glitching out on this laptop, but you can see here that all of the batch sizes are just 10% of what was advertised in these peakd posts.
Is the typo for batch sizes in the peakd posts or in the Glint shop coding?