I'd say a lot of activities like this can be done for cheap or free. Taking an elderly person to the park is free, it just costs time. Binoculars are ubiquitous, and bird books are a dime a dozen in your local charity shop.

The critical thing is that these people need a hand to get out of the house or do any kind of activity. And I think that's partially behind a lot of ailments that affect the elderly, they don't go out, don't get physically, mentally or sensorily stimulated enough so they atrophy in all those areas. On top of age related conditions like senility, parkinsons, altzheimer's, etc of course.