Here are a couple of sites that have various styles of tug toys for sale.

Crash test toys - They're a Canadian based company and have many different styles of tug toys both with real fur and fun fur. I got some for the Goonies (mainly the little boys) and they just love them.

Clean run -A company from the states that sells stuff for dog sports.

They're also fairly easy to make or at least so I've been told. Most of the tugs used in agility or flyball are made of fun fur or fleece which can be purchased at your local fabric store. You just have to take some strips of the fabric and braid them together.