Twilio + Google App Engine` is a combination used in the development of `Price It by Phone`, a service that allows users to comparison shop for books on Amazon.com using their touch-tone phone. The application uses Twilio's API to send REST requests to Amazon Product Advertising API, passing ISBN numbers and receiving responses with book data, which are then processed and output as spoken results. The application also stores the ISBNs in the Google App Engine datastore under the caller's phone number. The development experience was found to be easy, with the Twilio side being about 25% of the work, although having another sample showing a web form for verification would have been helpful. `Price It by Phone` was built from scratch over two days, using code written in App Engine and jQuery.