We did manufacture extra dice. The high manufacturing cost and lack of retail packaging mean it's not viable for us to sell these through the usual distribution channels to local stores. However, while supplies last, we will sell them direct by mail, at conventions, etc. The price per set of dice is $10, with shipping cost of $3 (US), $9.50 (Canada) or $13.50 (anywhere else).
We've set up this button to take orders directly through PayPal: