Not so much time ago speeds of 1 MHz would be considered luxury and only a few people had such instrument in their hands. The market, for a relatively low price exposes now 100 MHz or a bit more so this doesn't look as a main limitation for whom enjoy the field.
With experience in the field a company called LeCroy presents now a unique product that impresses for being the fastest in the world and its characteristics, capable of going further taking accurate measurements in a range that is microwave radiation. Those thresholds come with a myriad of challenges only for experts.
Its price? well, it's better not to ask. There's also competition for the highest... and perhaps the numbers are a bit funny for foreigners. Anyway, the following video could be interesting to know about some of the highest tech available and potentially the origin of future discoveries.