Hi everyone, I don't have a sick budgie but I wanted to ask some questions about budgie health.

Because of how cheap budgies are, alot of pet owners won't take or cant take their budgie to the vet, but then one day their bird is all fluffed up, and sleeping alot. Then, it dies. Look up sick budgie on YouTube and read the comments.
https://www.google.com/url?sa=t&sour...HHf8Erfu3LGnXg
I don't want this to happen to me, how can I prevent my budgie from ever getting sick? Humid or dry air, stuff like that.

Also, if one day this were to happen to me, how can I fix it? What steps can you take? Are there medications I can use from a pet shop?
I just want to be prepared, so that if my budgie is sick, I can stay calm, because I know how to make it feel better, and know that it won't die.
Thanks everyone for your knowledge!