Hello Powerstroke,
The fact that the boat has touched the bottom suggests the owner has been a little careless or unlucky. Check the fin, strut and rudder areas for damage or repair. There have been two (older) Boomerangs on Ebay. One had hit hard enough to drive the fin through the bottom. The other had been underwater. So these things do happen.
If it all checks out and you like the layout of the boat then I would say it is a fair price. Keep in mind that it is and older design despite being a 2000 model. The industry has moved on alot in the last few years. As noneya says, it is primarily a ski boat. If you want more wake, there are other designs that may suit you better.
I debated the purchse of my Boomerang for quite some time. No regrets. It has been great.
Tony