A fish arrow, some sort of holder for the line and some carp are all you need to go out bowfishing.
You can start with just a basic hand-wrap reel. It's slow and your range is limited.. but it works and it's cheap.
I use a retriever reel. Faster than a hand-wrap and sturdier (in my opinion) than a closed-face reel. The closed-faced reels give you the greatest shot distances and fastest retrieves.
I use fiberglass arrows with muzzy carp points.
Check out
http://www.keystonecountrystore.com/ they have a decent selection of bowfishing stuff... and they are a HuntingNet.Com sponsor.
I highly recommend using a 'Safety Slide' or 'cabled' arrows. While I know people who still tie to the back of the arrow, that can be dangerous.
Oh and just a warning... but bowfishing is highly addictive
Yesterday's outing..