Seems to be a $50 bonus for console trade-in. For Xbox One, at least. Didn't try others yet.
$170.10 for working Xbox One with power supply and no controllers ($10 extra per controller, so not worth including), plus $50 Dell promo egift card.
Edit: yep, $50 bonus seems to apply to all console trades. Xbox One actually trades higher than PS4. 360 only gets $10 before promo.
Edit 2: "Limited Time: Trade in your old PC and get a Dell Gift Card. Plus for a limited time, get a bonus Dell promo eGiftCard for an additional $50 off new Dell PCs & electronics." Not sure if that means the bonus is more of a coupon (may only apply to new PCs and electronics) than a gift card. Could just be poor wording.