Callaway Golf Pre-Owned cuts up to 50% off a selection of men's and women's pre-owned golf clubs as part of its Warehouse Sale. (Discount is reflected on the product page.) With deals starting at $8.99, that's the best percent-off discount we've seen from this merchant this year. (It offered a 25% off any single item coupon last month.) Shipping starts at $9.95. Some exclusions apply. Deal ends July 30.
A best bet is the used, "average" condition Odyssey Backstryke 34" 2-Ball Putter in Black Nickel (pictured) for $61.59plus $9.95 for shipping with free shipping via coupon code "RMN50SHIP". That's $28 under the lowest total price we could find for a new one. It features visible face alignment, forward press stabilization, and comes in 33" to 35" lengths.
Update: Orders of $50 or more qualify for free shipping via coupon code "RMN50SHIP".