Sleep with Memory Foam 2 Night via eBay offers this 14" Memory Foam Mattress in King or California King for $399.99 with free shipping. That's $127 under the lowest total price we could find for any 14" memory foam mattress in either size elsewhere, although we saw it for $2 less in our March mention. It features an 8" high density supportive base foam, 3" core foam support structure, 3" cool memory foam top layer for air circulation, and more.