Excluding textbooks for classes, I bought this for ~$300 (several several years ago as a special treat)
Most of my collection is thrifted/bought from garage sales (for a quarter to a dollar usually) but I do have a handful of nicer ones.
35€ on feefal's art book and I think 30€ for Al Pacino's biography, translated, as a gift for my mom.
Most books I buy are old and generally cheaper.