It's a fair price for sure, especially if the dock is included. As for if it's a good machine, well, yes, but it is an older machine so it will run slowly with newer software. The plus is parts to upgrade it will be cheap now, so you should be able to maxx it out without too much trouble, but that won't speed it up much for modern apps. Plus keep in mind it is under the requirements for Leopard (667mHz is 200mHz shy).
The pluses? The price is pretty good provided it is undamaged/works perfectly, and it will run Tiger quite well. One of my graphic design partners works in CS2 on a similar machine, and it's a bit slow but it works fine. Basically, if it covers what you need, go for it. If not, or if you want something faster in a less pro-grade, you should be able to find an ibook in the 867-1ghz range for about $50-100 more...