My opinions:
You most always spend more than you will ever recover in this hobby.
Buying collections locally from facebook marketplace or craigslist can be a good way to acquire a lot of cards pretty cheap but you might get a lot of cards you didn't really want to collect.
I think if you want to collect cards that can sustain value you are better off buying vintage stars. I don't know that they will go up but they have mostly settled in at their value.
Buying new and buying new packs is a money pit and if you want something to sustain value this is not the way to go.
If you want to collect vintage stars like Gretzky, Hull, etc. you can probably buy their older cards and they should hold thir value quite well.