I think the pricing starts at $19k/yr for a 10-node cluster (so $1900/yr/node). That's what I was given as "list price" when I asked, we are not using 10 nodes yet, but I anticipated that we'll need paid support before we are, and Tectonic is one of the only games in town.
I'd guess you can negotiate that down somewhat, especially if your shop has some expertise in-house already (if you're not anticipating a lot of need or demand for their support team's help on a regular basis.) We compared this to RedHat+AWS OpenShift Dedicated which is priced significantly higher at $12000 for 4 nodes, on a per-node basis, but also OpenShift Dedicated has already built-in the cost of hosting the nodes.