chugh

I think it's really up to your study style and what you think you'll find useful in the future. I bought my first PH textbooks (used), such as Intro to Biostatistics. I'm in Epi, just finished my first year. I thought I would reference it more than I have, but maybe the book will still be useful in the future. You seem to have a good starting point--buying what you think is useful and renting the rest.