I'm rather new (most a come back after years than a fresh new player), so... Currently, I have everything sorted by color and rarity in already full 9x 1k cards box (one for each color, on artifacts, on multicolor, one for the lands and the latest for pre-modern cards).
I mostly plan to sort them all, pack the one I don't see using one day and give them to new players, after that they will all go to double sleeve. I just have 3 binders, one for the planeswalkers, one tiny for the gods and the latest for all the commanders. That's the only collecting part I have, out of that, I mostly plan to put all the cards in playable deck or the cubes I work on, ideally I want a collection of deck with enough variety in them that I can use them to teach / play with friends at will even if they don't have cards.
(in that, the most expensive part is the sleeving... That's depressing
)
And finally, for the most expensives cards that I don't see use for playing, they usually go from the classic booster, to sleeve, to selling/trading site to shipping.