"Decent" or "adequate"...? If you're just getting going, you can pick up an OK one for £25. My ex-singing teacher (who originally went to the RCM as a violinist) spent £1K on a carbon-fibre one about 18 months back. I'm on the £25 end myself. ;-)

Playing with a crap bow is like playing a guitar with bad action. You can probably make it work, but even as a beginner, the bow will be limiting what you can do. It doesn't need to be special, but it needs to *work*. Head down to your nearest classical music shop and find a proper bow.

Note that baroque bows *did* curve like an archer's bow in the middle. It's vaguely possible that you've picked up something that was previously used by an early-music enthusiast, so don't just chuck the old bow away until someone else has made sure you're not binning something valuable!

Graham.