99 cents via eBay offers the Sticky Pad Anti-Slip Mat for $2.99 with free shipping. That's the lowest total price we've seen for an anti-slip mat with a "v slot", and a current per-unit price low by at least $1. The "v slot" holds most cell phones upright in landscape mode.
Allow two to three weeks for this item to arrive.
This tropical nation is practically perfect for anyone open to leaving the U.S. in hopes of dramatically cutting costs.