This will come down to specific features you might be looking for, but on average between anywhere from $80 to $150 is pretty good pricing for a soundbar. Prices will also obviously be far more affordable during the holiday sales season, so you could even see up to $100 off select products, so again this all is dependent upon what kind of soundbar you might want.
Additional features, like optical, HDMI, and AUX options will typically be around or higher than $150, so keep that in mind while looking for your next soundbar.