Disposable cameras were an invention of Fuji and Kodak in the mid 1980s. They are smart to keep in the glove box in the event of an accident; less risky to take on vacation; and a great favor for capturing all those wedding moments. This is common among disposable cameras on the market. You can get both digital and film disposable cameras.
Disposable cameras have a housing, usually made of plastic covered with cardboard, which as such has no provision for being opened. This is kind of similar to disposable digital cameras. Disposable cameras are called disposable for a reason. Prices will quickly fall as vendors compete for market share.
Disposable digital cameras are cheaper than the regular digital camera. Of course this is like a disposable underwater camera. If you a professional photographer however your probably looking at Digital SLRs and if your just looking for a good Sony or Canon camera you should research the models and review them making sure you select the one that is right for you. For this reason if you take a couple pictures, you cannot go back and erase the first or second one.