I've begun adding a number of rare books to my bookshelf and am rather excited about them to be honest so as I add more I will share them because of autism
Foundations of Analysis: The Theory of Limits - Herbert S. Gaskill & P.P. Narayanaswami
Good condition versions cost around $70-$100 USD and I got this one that is marked up for $33.
It's a decent edition but it its from the library of UC Santa Cruz as such it's not worth as much as other editions. I had bought another version of this text, a much cleaner edition in great condition, but unfortunately it got lost in transit. Nonetheless, I am ecstatic to finally have it in my hands as it is one of the most comprehensive texts ever written on the Limiting process.