These are relatively cheap and come in various guises, such as food storage tray liners for fridge, plastic apples filled with absorber, 'stayfresh' bags, and sachet type packets. Some of them use a coated zeolite, which has a honeycomb like structure which absorbs odor and ethylene. Depending on type, the absorbers last about three months to a year in constant use. When not in use, they can be stored in an airtight container almost indefinitely, for later use.
There is scientific evidence that absorbers are effective and growers would not waste money on technology that does not work. A US Navy test showed a 245% improved shelf life for tomatoes, 88% for lettuce, and 10% for cucumbers. All indications are that they work best in closed area, rather than simply putting an absorber on a counter next to fruit. They can be purchased online and at Walmart, Bed Bath, etc. I read many comments from users and they appear to work as advertised, which is a pleasant change these days.