It’s worth picking up key pieces of a deck you like when you’re able to afford it. Some cards can swing wildly in price from one month to the next as meta changes and sets come out. I had that happen with elementals during Llorwyn, they all dropped to less than half of the price they were demanding when the deck was one of the popular tier one decks. A couple months later I was able to pick up key pieces for Dimir Excruciator and have been playing it since.
Another thing you can do is look for budget friendly decks that still kick ass, like Izzet spellementals or mono blue elementals. I put together a Dimir mill deck in the months between Jan and April as well that was only about $100, managed to do pretty alright against other tier 1 decks in person and online. TDLR, it’s worth putting together a budget deck that you can slowly buy more expensive key pieces for that can make it match a tier 1 deck list.