Yeah, drop bar Ti frames with room for 2.4 29er tires (a very cool and desirable idea for me as well) are not exactly thick on the ground. Custom or boutique is likely the best option with bikes like the Moots Baxter or Mason ISO. I'm going to assume that since you're balking at the price of the Salsa, something like a Moots isn't going to work either. Steel, carbon or aluminum open up lots of somewhat more affordable options, for example:
Hook ADV 2019 ? Bombtrack or
https://www.honeybikes.com/packmule-...acking-series/ or . Also, you could build up a "traditional" Ti 29er frame to be drop bar assuming you by one with a short reach and a drop bar friendly front end. This is going to take some hunting, though.