Home Slickdeals Costco In-Store Offer: T-Mobile Samsung Galaxy S9 + Up to $360 Trade-In... Slickdeals Costco In-Store Offer: T-Mobile Samsung Galaxy S9 + Up to $360 Trade-In Credit $680 (after Online Rebate) By ARCOM - 16 March 2018 172 0 SHARE Facebook Twitter Go to the deal page: Costco In-Store Offer: T-Mobile Samsung Galaxy S9 + Up to $360 Trade-In Credit $680 (after Online Rebate)