T-Mobileis offering at least $ 200 for trade-in of any 4G phone and a free B&O headphones, and sell the V20 for $ 770, so at most $ 570 (+taxes). In addition, you can get a free LG Tablet if you also sign for an additional data plan for the tablet for 2 years (for a family plan, that means extra $ 240 + taxes).

Link to the T-Mobile Page