I would not break the bank to go from 100-200MHz.
Most experiments and insights for an beginner into analog could be gained with a 1MHz scope... Just pick your values and frequencies accordingly. E.g. doing the AoE coursebook, did you find something for which you actually need a digital 100MHz scope?
I started with a 30MHz analog Hameg scope which I got for 20 bucks, lasted me 2 years. After that I knew what I would need and bought me a digital scope... That was about seven years ago.... Now I have a 2GHz and a 5GHz scope on my bench, but thats more of a TEA issue
Anyway, you seem to be kind of in between. You did some stuff with simple entry level solution but you did not yet figure out whats really important to you. Otherwise you would not ask. So if I were you I would wait or buy something used which you can sell again. Those chinese scopes are great bang for the buck but their resale value is terrible...
For digital stuff on the other hand I would recommend a decent USB logic analyzer. I never used digital channels on my scope even when I did have them. If you do Arduino stuff and you do not yet have one, invest here first.