Walmart offers the Eccotemp L5 Portable Tankless Water Heater for $89.99 with free shipping. That's the best price we could find by $17. It features battery-powered ignition (via two "D" cell batteries), 20 to 80 PSI operating range, and up to a 1.5-GPM flow rate.
The dollar store is the most amazing place to find bargains for certain purchases. Yes, even pregnancy tests.