Gacha gacha machines exist throughout Japan. The popular gadgets crank out all sorts of interesting toys and figures to whoever drops a few hundred Yen in the slot and turns the crank.
Unlike the quarter or fifty-cent machines loaded with crap like cheap rubber balls or flimsy plastic rings once common in supermarkets through the United States, Japanese gacha gacha machines are full of very high quality products. They are usually made of high-grade PVC plastic and have a high level of detail.
Gacha gacha machines are variously themed. Each carries items from a particular line. Each line is made up of a variety of objects, with some being common and some being very rare. Items from Japanese manga comics and cartoons are common, as are other characters. But there is also a wide variety of interesting and weird lines made up of things ranging from "the animals of the African plains" to "drunken businessmen.
There is a very large second hand market for gacha gacha items in Japan. Whole floors of the huge Nakano Broadway Mall in the Nakano section of Tokyo are filled with gacha gacha shops. In Akihabara, the traditional "otaku" (geek) section of Tokyo, there are giant buildings with several floors filled with nothing but gacha gacha items.
Not hardly just for kids, gacha gacha are popular will all walks of life in Japan.
Some second hand shops are individually owned. Others rent out small cubes to people on a monthly basis for a few thousand yen. The renters then fill the cubes with items they wish to sell. The shop owner handles the transactions and pays the renter at the end of the month.
Some items can go for thousands of yen based on their rarity, even while the lines are still available in machines.
Gacha gacha machines can be found all over. The popular Yodobashi Camera stores (which sell a lot more than cameras -- they are comparible to Target stores in the United States) usually have huge gacha gacha sections.
The Bandai company holds the trademark for the term gashapon. Onomatopoeias are very common in Japan, and "gashapon" is just one of many. The word is meant to emulate the sounds made when one turns the crank ("gacha") and when the capsule falls out ("pon").The name "gacha gacha" is a more generic (and common) varient.