Digital camera progress and depreciation

When we bought our digital camera 4 years ago, it was a 2.0 megapixel, going for $300. It has a video feature (a couple minutes then the memory is full) and a couple other nice features. But compared to the digital cameras of today (you can get a 7 megapixel for $150 or so) it's thick and clunky and outdated already! I must give kudos though, like our 9 year old computer that we just recently had to retire, the electronics we've chosen over the years seem to have incredible lasting powers!
If you can believe, I just saw an advertisement in a flyer today for a no-name UNDERWATER digital camera for $24. Whaaa??? It didn't specify the amount of memory or megapixels, but wow...that is cheap. And underwater? How does that work without wrecking it? I think I have to check it out nonetheless, I'm intrigued!

It really does amaze me how certain technologies advance in performance capabilities and decrease in value over such a short period of time...