A 16Tb manufacturer recertified drive is USD160 which should sort storage (and later get a second for offline backup). I'm actually holding out until I get GPU encode (apparently CPU is somewhat better, but power considerations, maybe next gen). Do wish the scene would get on with switching, though, are we dinosaurs?
AV1 is really only practical for content that has a high quality source like a bluray release. Most streaming sites aren't using AV1 yet, so anything from them would have to be transcoded. Transcoding a low bitrate source to another format will cause a loss in quality. It's not really worth it unless you want really small files to watch on your phone.
AV1 hardware acceleration is becoming fairly common, so I wouldn't be surprised if the streaming sites start switching to it soon.
As a note, AMD 7000 series GPU for AV1 encode, the encoder is flawed and can only produce factors of 64x16 pixels, as well as a special 1920x1082 ratio. If your have a lot of 1080p content, it will be recorded with two lines of black pixels on the left and right, and then set to crop it out on video playback.
Just something to keep in mind if you go with that series of GPUs.