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.
I spent $120 $282 on the paperback set of WoT and that is also my most expensive "single" book purchase.
Edit: Nope I lied. I spent $120 on the ebook set, the paperbacks were more expensive.