A/C Fan Issues?

Forgive me for not using any super technical language in advance--I know very little in terms of cars and will do my best to describe the issue. Really wanting to get an idea of what this problem might be before I take it in to the dealership so I can have an estimate of costs and whatnot.

I have a 2008 Toyota Prius, Touring with all the bells and whistles (up to package 6, I think).

Brief history of the issue:
Back in May of last year, we took the car on a trip from Texas to Florida. It had roughly 95k-98k miles on it when we started out. The vent fans started going in and out (literally not blowing air at all) and we were hearing some knocking noises. We took it to the dealership (because it was summer and not having a fan would be gross) and it turned out to be a problem with the water pump, so that was replaced, and the car drove back to Texas fine.

I'm experiencing a similar issue now where the fan goes out intermittently (car is now at ~105k miles). This happens regardless of what temperature it's set on, A/C or not, auto or not, fan speed, which vents are on, turning fans on&off, etc. When the fans ARE working, they seem to be making a buzzing or humming noise (that seem uncharacteristic to me; I've been driving the car for about 4 years). I can turn the fans off completely and the buzzing noise goes away.

Up until recently, if the fans didn't come on until the car started, I could drive for about five or ten minutes and they'll kick on. Sometimes, when the fans do not come on initially, I can hit a speed bump and it will jog the fans back on. Other times, I have to let the car sit for several hours (parked and off) before the fans will come back on.

At this current point in time, my car's fans are coming on less and less, and when they do, the buzzing noise seems to be even louder. They weren't working Friday afternoon, and I let the car sit over the weekend. They worked again this morning, but now they've kicked back off and won't come back on no matter what I do.

I'm hesitant to say it's an issue with the water pump again, because I don't hear any knocking like last time. From what I've seen from perusing here, it may be a blower motor issue or an air compressor issue, unless something else is to blame. What seems most likely? Additionally, would it be a fairly easy fix for a noob or should I bite the bullet and have a professional fix it up? I'm definitely looking to save money, but I don't want to endanger the integrity of my car if I unintentionally mess it up.

Thanks so much! Apologies if this is too similar to a previous post!