Yes, as of 2015, window air conditioning units can be purchased online from home improvement retailers such as Lowe's and The Home Depot. Retailers offer a variety of shipping options, including in-store pickup and direct shipment.
Both Lowe's and The Home Depot offer search filters within their heating and cooling product listings which include window air conditioners. One particularly helpful way to sort through the product inventory is by cooling BTU ratings, as more powerful units with higher BTU values are ideal for cooling larger rooms. Retailers also allow shoppers to sort the available units by numerous other factors including price, brand name and the presence of various energy-saving features.