An easy and inexpensive way to protect a camera from blowing sand ('sandproofing') is to enclose it in a plastic bag with the lens protuding -- provided the camera can be fitted with a photographic filter, as is usually the case with DLSRs, video cameras, and even some point-and-shoots. For example, the Canon A570 IS shown below has an optional filter mount that fits around the lens, to which a filter can be mounted.
This also works for protecting a camera from sea salt spray (mist) at ocean coasts.
Here's how:
Get some elastics ('rubber bands') and a plastic bag; a bag that is long and narrow works best. It should be thin enough so that the camera's controls can be manipulated 'through it' and tough enough to resist tears.
Even if it is transparent, the LCD will still be hard/impossible to see in daylight, so the bag needn't be transparent.
The bag in the photo to the left was obtained from a bulk food store (intended for bagging spices); it's just an ordinary bag. A bread bag is a good shape.
Put the camera into the bag, facing the bag's opening.
Stretch an elastic band over the neck of the bag and position it along the edge of the filter.
The elastic needs to be tight, as this will be sealing the camera from sand. Multiple elastic bands are a good idea.
Leave some slack in the bag around the camera so that the camera's controls can be set by manipulating through the bag.
Roll up like a sock the excess of the plastic bag, and flip it back over the camera lens (or cut off the excess, leaving a few centimeters of bag to flip back).
Hold it there by stretching an elastic over the flipped-back bag.
You're done!
The controls can be manipulated despite being covered by the bag (but be gentle, to avoid breaking the bag).
Here's what it looks like from the back.
The LCD looks like it would be visible, but in sunlight it's pretty hard to see (even without the bag). The phrase 'point and shoot' becomes particularly apt; but it works.
Features of the above solution include: There's nothing optically-distorting in front of the lens; it's easy to find a plastic bag just about anywhere; when you are done, the materials are disposable (nothing to clean or that can retain sand, etc).
Here's a video camera:
Of course there are more 'industrial-strength' commercial solutions such as using an underwater housing, but those are usually expensive, sometimes costing more than the camera, and not transferrable if you get a new camera; a housing might not fit your lens, etc.
Another solution is a plastic pouch: Aquapac makes one, and a web search on 'waterproof camera pouch' will turn up many others. I haven't tried them and wonder how long the clear plastic would remain clear and unscratched; the above has worked well enough for me.