WholeSaleGateOpener via Amazon offers Prime members the Best Choice Products Electronic Digital Lock Keypad Safe, model no. SKY163, for $39 with free shipping. (Non-members can spend $49 to bag free shipping; otherwise, shipping costs $12.52.) That's the lowest total price we could find by $15, excluding the mentions below. It features a 1/8" solid steel case, 3/4" pin bolt lock, 2" thick door, and a hidden lock mechanism.

A close price: Best Choice Products via Walmart and Jet.com offer it for $39.95 with free shipping.