As far as I know, practically the only way to get sexed bantam chicks in the U.S. is through one or two hatcheries unless you get very lucky with the breeders in your area. Last I checked on one of those hatcheries (MyPetChicken), they charge around 15-20 USD per sexed female bantam chick, plus a substantial shipping charge, which quickly adds up. On top of that, sexing day-old bantams usually ends up being less accurate than sexing large fowl chicks, meaning that despite paying extra for females, it's pretty likely you'll end up with a male among your chicks.
Getting older pullets or hens isn't always simple, either. In my area, at least, hardly anyone sells bantam pullets or hens alone. You get pairs or trios, sometimes quads if you're lucky, so at least one male per every 1-3 females. Same goes for any rare or showy breed of large fowl. In places where roosters are disallowed, this makes it near impossible to get adult bantams because those boys are already crowing and will cause problems with the neighbors.
Getting large fowl egg laying hybrid hens is easy, though.

I've seen those go for as low as 5 USD a head at point of lay.