Jon Elson writes:

Aperture? I'm pretty sure NO digital camera in the $200 range has an
aperture, ie. an iris. I think you have to get into the $2 - 3K range
before thay have that feature. All the under $1K cameras I've seen have
no shutter, no iris, and most have a pretty primitive optical zoom
system, too.

I think the Canon A70 is the cheapest digicam with full manual
controls, including aperture and shutter speed ($200-$300
depending on where you buy it). It can take good pictures if you
respect its limitations (slow lens). Their S-series cameras are
similar, and cost slightly more. The G-series has a better lens,
but it costs $700.

They use a combined shutter/iris mechanism.
Certain shutter/aperture combinations are unavailable because
it can't open and close fast enough. This seems to be common
for cheaper cameras.