12speed drivetrains are still new and as such, still pretty expensive. It is only recently that Shimano released a lower cost 12 speed MTB system and Sram has had their lower cost MTB systems in place for some time. At this point there is only Campagnolo and Sram that offers 12 speed drivetrains for drop bar bikes. Neither of which is considered cheap. There is a 13 speed set up but it's even more expensive.
The Sram Force/Red AXS controls with an Eagle AXS derailleur is really the only 1x12 system available.
If you wanted to save a few bucks and not replace your brake levers or calipers you could use the AXS Eagle derailleur with the blip box.
Sram Blip Box $385
Sram Etap remote blip switches Not necessary but would be nice, $110
Eagle XO1 AXS derailuer $700
Add on the chain and cassette of your choice and that would do it.
Just as an FYI:
Sram Force HRD AXS controls $495 each for front/rear