That isn’t a large markup for a36 at that size. Not sure of the thickness, say 1/4.
Yea it is a large markup, a very large markup, it’s ridiculous.
https://www.ebay.com/itm/193466603638
1/4 x 12 x 16 for $18 + $13 shipping.
Or use a cast iron skillet or griddle. They have the same cooking effect and maybe you have one on hand already.