I see that you've made your decision, but thought this thread needed mention that nearly ALL bbl makers have the capacity to make 46" bbls.
But yes, anything that isn't part of a production run will cost more. Setups are time and money. Running 100 of something spreads that cost out. Running one...doesn't.
I got mine (30x46xA) from Charles Burton and have inquired with Jason about his capacities to run longer...Ed hasn't made me a bbl yet, but that's a goal. And I have no plans of going shorter than 46 again.
Some folks can't handle the time factor, others the $. But pretty much ANY bbl configuration you want is available with enough of those two factors. Plan ahead if you're going to make a bunch of guns (stock up on bbls ahead of builds).