The manufacturer New Sensor / Electro Harmonix sells the tubes on their own online store. Their prices have increased drastically in the past month or 2. Take a gander - KT120 for $150 each. Gold Lion KT88 $170 each. You can imagine the KT150 and 170 prices. Between double and triple the previous "usual" prices, across the board. That may or may not be indicative of prices going forward. But in a worst case scenario, those are the "new" tube prices, and any onshore vendors selling for anything less than that are simply burning through existing stock on hand.
In a better case scenario, these are just temporary price spikes intended to keep hoarders from wiping out existing stocks before we get a better picture for the long-term prospects of Russian manufacturing.