HELP! I am a single woman and I need some good advice.

My 1991 300CE with only 38K miles is in trouble. My engine was making a little bit of a rattle noise so I took my car to the Mercedes Dealership. The Mercedes Dealership tells me that I may need a new timing chain and rails. They will check it out by taking the valve cover off at a cost of $230. (this is just to check it)

The dealership replaced the tensioner and feel that a visual inspection of the chain is a good idea. They are concerned about the rails due to the tensioner problem that they fixed. If the chain need to be replaced they say that it takes 7 hours of labor. Total cost including chain and rails of around $1,400.

Does this sound like the right thing to do? Does the cost seem correct? Any help would be greatly appreciated.