Breech ejectors are cheap considering they do something that is nearly forbidden in pf2e: getting extra actions. Paying 10gp for one action is nuts, even as a consumable. They aren't worth using at the level you have access to them, but at higher levels the pf2e wealth curves means that using 2 breech ejectors per fight is really nothing. The issue with quick drawing replacement pistols is that there is no way to apply your weapon runes to quickdrawed ranged weapons; there's an item for melee weapons, and an item for ranged weapons, but the item for ranged weapons requires that you attach it to the weapon, requiring time. If you aren't getting the benefit of fundamental runes, you are dealing no damage at higher levels.

With that said, firearms in pf2e are pretty gimped. The "best" gun using builds use sniper shot and a tripod saddle or whatever it's called to fire the biggest gun you can get your hands on 1/turn with sniper shot and covered reload. But generally repeating crossbows are superior, since they probably won't need to be reloaded before the fight ends or you've dealt enough damage to cinch a win without taking a turn to reload mattering.