Yeah, well, SketchUp isn’t really a ‘edit random free ■■■■ I download online in non native formats’ sort of tool. So if that is your goal, yeah, don’t buy it… 
You might have better luck looking for things on the 3d Warehouse, at least you’d be working in a native format, but the quality on the 3dW can run the gamut from tight clean and optimized to ‘let’s export our entire catalog to SketchUp out of this other program no matter how big the files and call it good’.
Spend some time with the tutorials. That model would take me maybe 5 minutes to create.