Some airlines have stores of their own wherein you can purchase things in-flight. IIRC, this was nudged at one time as a sort of "duty free" experiment by a few airlines (Icelandair has such a program: http://www.icelandair.us/information/on-board/in-flight-duty-free/)...but I think it has only been a thing with airlines that do mostly trans-oceanic international travel (and presumably with cooperative corporate domiciles that are happy to let them dodge any tax hassles).I recall that on some flights, you could actually purchase and receive certain items right on board from the flight attendants....not sure if that was thru the Sky Mall or directly from the airline.....I purchased a unique pen with a built in light.....![]()
The biggest issue SkyMall probably faced wasn't that people weren't buying the stuff...just that they weren't buying from them. Basically they had a "showrooming" problem (i.e. someone wants the Harry Potter wand but instead of going to SkyMall, they go online, check prices, and buy direct from the seller and thereby cut out SkyMall)...and they're not the only one (Circuit City, Best Buy, and a lot of others have had that sort of problem).