Hahaha, good luck
Most of us become disc crack heads. I can't even go into a shop without buying at least one disc that I don't need.
But, I am also sure you have plenty of decent discs to practice with, because you can use any of them. Figuring out what discs do for you at any given time in your learning is a lot of fun. I assume you aren't going to solely work on form, and still want to play the game itself. You probably shouldn't expect to use higher speed drivers in their intended way, but as 100% reliable beefcakes that will always fade hard, there is a use for them in your actual gameplan.
For disciplined goal oriented field work, I think I would have benefited from learning how to throw putters sooner. Throwing a neutral putter on a rope 200' would be an amazing goal that will set you up with a lot of workable knowledge to apply to other shot shapes. Having 5-10 neutral putters is worth the investment in that pursuit imo. The mold itself doesn't really matter too much, there are tons of options and Im sure you can find used discs that will be fine. Basically any putter that doesn't make you recoil in horror when you hold it is going to be ok.
I don't find mids to be much different than putters, they just go farther. Faster discs do start to demand more nose-angle control, so I wouldn't avoid them. You said you had a few understable drivers, like the Orbital. Keep tossing this one until you can reliably make it turn over from a slight hyzer. Its a faster disc, but it is also quite understable, and I could see it being a decent one to learn with. I bag one myself, but I live at high elevation and it is not nearly as silly as the numbers would make it seem.
Also, remember that disc flights are very dependent on who is throwing them. If you want to get neutral flights out of discs that are not being thrown very far, you will be looking into discs that are quite understable. Don't get too frustrated if you can't get flights that match the flightplate numbers out of all of your discs for a while (or ever really).