On the other hand, if you compare it to other drawing packages offering similar capability, the price of Sketchup pro isn't so bad.
Usually when I see this kind of discussion come up on woodworking forums, somebody chimes in and says the best program for 3D drawing is Solidworks. I did some price checking last summer and found that SW is more than 10 times the price of SketchUp.
There's much more to pro than just importing/exporting CAD files but as I said many times before, if the free version offers the capabilities you need, there's no point in going pro.