Adorama offers the Korg B1 88-Key Digital Piano, model no. B1BK, for $499.99. Coupon code "1APRILSVNG" cuts the price to $419. With free shipping, that's the lowest total price we could find by $81. It features a hammer keyboard action, eight demo songs, and includes a music stand and damper pedal.
Of note, it's available bundled with the Korg STB1 Piano Stand, model no. B1BK A, for $599.98 before the above coupon, $489 after. With free shipping, that's $111 under the lowest total price we could find for these items purchased separately elsewhere. The stand places the B1 digital piano at standard keyboard height.