The best price found from United States to Puebla is on September 28th, 2018, travelling with United. See more options, compare prices and book: search flights.
Aeropuerto Hermanos Serdán, 22km northwest of Puebla off Hwy 190, has Aeroméxico, Volaris and MexicanaLink flights to/from Guadalajara, Tijuana, Monterrey, Cancún and Hermosillo most days. There is one daily international flight to/from Houston with Continental; and one to/from Dallas with American Eagle.
Service can be patchy and the airport closes whenever there is volcanic ash in the air. The Toluca airport is likely a better option.