I bought a little Vellaman 5MHz scope a few years ago, its been very handy for the windmills. 5MHz or 10MHz is more than enough for this type of industry, you only need to go to 20MHz or higher if your testing radio equipment or other high speed electronics.
I did have a 200MHz Tektronics 485 a few years ago, but never used the higher frequencies. It was a nice cro, but more than I needed so I sold it on ebay for a few hundred dollars. I now have the Vellaman portable and a bigger 20MHz bench dual trace.
Glenn