As has been said, if an acoustic bass is to be used truly acoustic it won't be heard above a firmly strummed single acoustic guitar!
I own a Washburn AB20 bass and it needs to be amplified if played with other instruments; fine for playing by itself in the house but amplification is needed in 90% of the situations where you'd need play an acoustic. However, if it is for that tone and you know you are going to be boosted then I hope you can find one soon.