Study Materials?

I am taking level I for the first time in June. I have already been studying for a month, and I keep reading that supplemental study material is a must. Should I purchase Schweser, Elan, Analystnotes, or Stalla? I have heard great things about all of these materials. I am not looking to spend $1000 for a completely different set of textbooks. I fully intend on reading through the CFA text entirely. I am asking for advice on materials to supplement those texts. i.e Qbanks, mock exams, notes, formula guides…(and which brand) My budget can allow me to spend around $500; what should I spend it on?

Personally I am using Elan guide study notes, but just search through the forum and there are a lot of great advice on what brand and what to get. Good luck!