yes, they are definitely niche. Thisvery site has around 1000 subscribers. You will not become a millionaire for sure, but if you make a couple of bucks from a subscriber a month, that's a nice addition to whatever else you are doing. They charge $25 for two envelopes of candy per month. I got a subscription to surprise my wife. But I will probably not keep it for longer than a month.

This is an interesting niche service; not sure how many people use it and how often, though. I think I will need it if I am in travel and am missing my ???.