What are the most frugal yet low-effort options for coloring hair?

My budget doesn’t extend to getting my roots colored every month, but I’m terrible at coloring my own hair (there’s a lot of it, and it needs to be done every 3-4 weeks because it grows fast, too). Even Supercuts charges $60 to color roots. I’ve considered hiring someone through TaskRabbit to help me.

I’m going to have to figure out something soon because I’m going to be looking for a job, and I’m feeling really insecure about job hunting in my 50s. Due to my general ineptitude with hair, I can’t cut it too short to put up in a ponytail.