Excursion is distortion. With that knowledge one wants a rigid driver that oscillates very little. Hence the proliferation of dome midranges, like on TAD and Yamaha speakers. That said they aren't particularly efficient or cheap. Beryllium's difficulties drove Yamaha to develop aramid drivers coated in Monel. There other "exotic" tweeter materials because of the aggravation of beryllium. Many have made peace with it.
Study your options. Do not be ashamed of your budget. Price is a criterion of degree of difficulty. If you speak another language look the model up on foreign sites you understand or can translate. Biases are hidden in adjectives. Also think about your listening space for sizing.