As of March 2015, the manufacture of Nova pizza ovens has been discontinued, making eBay the best place to find a used model. Occasionally, a liquidator such as GovDeals.com has one listed for sale. Nova pizza ovens are extremely popular, so when one becomes available, it sells quickly.
Novas were originally produced for the Tombstone Pizza Company in two models. The N-100 is the most common and is designed for thin-crust pizza, while the N-300 is designed for deep-dish pizza. Comparable models from other manufacturers are available on both Amazon.com and eBay, such as the Wisco 412-3 wired countertop pizza oven by Wisco Industries.