A few years ago, I spent most of my savings on The Lunar Chronicles by Marissa Meyer (Cinder, Scarlet, Cress, Winter, and Stars Above; I didn’t get Fairest), read them all, and loved them…though I didn’t reread them and sold them some time later.
And what was the first series you spent most of your savings on?
Horatio Hornblower Saga. All 11 books.
Eta I had a lot of series when I was a kid. Rats of NIMH, Misty of Chincoteague, Little House, etc but I never bought those, my family did. Had a ton of Dragonlance books, but no where near the whole series.