Can’t buy output tubes anywhere except from manufacturers at high prices.

You might try Eurotubes. www.eurotubes.com. I have bought many tube from them. Great people.

@bigeks357 -  I've used VivaTubes they are a reliable vendor.

@hiendmmoe - You haven't stated either the amp(s) that you are interested in, or the tube compliment of the amp(s) that you are considering; it would be helpful to know so folks can maybe help point you vendors and/or brand options. For instance, while the TubeDepot and the TubeStore are out of stock on some brands of KT88 & EL34 tubes they have availability in other brands. Likewise, vendors such as Sophia Electric appear to have KT88s & EL34s, VivaTubes has availability, PremiumVacuumTubes has KT88s.  The KT 90 KT120 & KT150 tubes maybe harder to source at the moment as there aren't multiple brands  However, VivaTubes appears to have availability of them at the moment. The TubeStore has KT150s & KT90s but not KT120s. Anyway, just some examples.

I’m unloading my matched KT150’s because they’re more power than I need. When I priced them for my ad, I looked around and there are lots of tubes out there.

The OP may feel prices for tubes are "high," but they are available and prices always fluctuate.

I was referring to Kt types and EL34. 

Especially KT types and 6550s. Their prices if you can find them have skyrocketed.