Officedepot.com has 24"x36" Aluminum framed magnetic dry erase board for $12.99 as part of their "Biggest Baddest Blowout Sale". The site allowed me to use the 20% off coupon bringing the price down to $10.39. It also stacked another 5% off for free in-store pickup to bring the final price down to $9.74 plus tax
Link: https://www.officedepot