Cheapest I could find online when looking for a reliable one.
Ring Automotive RINVU150 12V Modified Sinewave 120W Inverter
• 120W continuous output to power a range of household appliances
• Modified sinewave output
• 240Vac output to power a product without additional converters
• 12Vdc plug socket to allow a single connection into a car accessory socket
• Weighs only 580g and its compact design (234mm x 234mm x 85mm) prevents it getting in the way
• 2.1A USB connection to charge an additional device such as a Smartphone or Tablet