60k pieces are hard to find in my experience, particularly the non-diamond ones.
Even though it only used one stone, someone had to have the funds to buy that many stones to begin with. This bug was around in 2000/2001 and gold wasn't as abundant as it is now. Not to mention they didn't have a 500 stock count on the vendor as I recall. They started at 20 and you have to build the amount (and I think the price went up as you did although I might be wrong on this).
Folks made pieces in amounts they thought would be appealing. These were round/even numbers such as 100, 1k, 5k, 10k, 20k, 50k, 60k. They also made novelty pieces for the years 2000, 2001, 2002 as well as 666 and 69. The novelty are more common than the larger 10k and up stone counts because they were cheap to make and the average player could afford that many stones.