$15
Great intro textbook to cryptography, in very good condition.
https://www.amazon.com/Introduction-Modern-Cryptography-Principles-Protocols/dp/1584885513?ref_=mw_olp_product_details
Cheapest used copy on Amazon is >$30 including shipping.
Pick up on campus, I take BTC/ETH/PayPal/Venmo/cash.
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