I have a 2003 Mazda Protege with about 100,000 miles on it. Even very uncertain guestimates at the appropriate price for this would be appreciated.
Will worn struts damage my tires? How quickly? Is driving on worn struts dangerous?
The way to tell if your struts are worn out is this:
Push down hard (lean into) the fender right above a wheel and then let go. The spring should compress when you push into it, and the car should come back up ONCE (slightly above the rest point) and settle back into where it was.
If your shocks are not doing their job, your car will bounce 2 or more times before settling, and should be replaced; mostly for handling/safety reasons. It's unsafe to bounce after a bump multiple times, especially when cornering. In an extreme case, you could lose traction and hit a wall because of poor shocks (but you'd have to be pushing the limits of the car's traction and then hit a bump while in a corner).
However, they shouldn't 'damage' your tires or cause them to wear any faster than normal. Wear is caused from friction with the road (length traveled), which will be amplified by a poor alignment.
I would 'guestimate' a shock-job at $150-$400 per pair (Front or Rear only), which will depend greatly on your car. Most trucks and some car rears are on the cheaper end (shocks) where most car fronts are struts which are a more costly part and more costly to replace (the spring has to be compressed and set into the new one).