Mytopo.com is very similar to Offroute, but with a less friendly interface. I find them harder to order from, but their prices are cheaper, especially for larger maps. You can order folded maps which are cheaper to ship. Compared side by side with Offroute, their map quality was a notch lower: colors less subtle and no relief shading. But their prices are hard to beat.
18″ x 24″ topo map