First, I purchased it 2 years ago. I like to buy in bulk and this was at an auction. I tend to find that large quantities of less popular calibers can be purchased relatively cheap if you are willing to spend a few hundred dollars at a time. You won't generally get $40 of ammo for $10, but you can/could get $700 of ammo for $300.
Of course, that was 2 years ago, but I was buying then in anticipation of now.