The last year that Weber made a Genesis Silver was 2005. I am writing this in 2015 so there is a slim chance that your burner tubes and side tables are still under warranty. The only components of your Silver that are absolutely still covered under warranty are the aluminum castings and the porcelain enameled hood.
The reason I am showing the warranty information is to help you figure out which replacement parts you want to purchase.
Let’s start with the Flavorizer bars. If you go with the porcelain enameled steel bars the original warranty was for 1 year compared to 5 years for stainless steel.
The stainless steel Flavorizer bars I have linked to in the parts lists are aftermarket Flavorizer bars that are even thicker than the official Weber bars. You can spend around $40 for porcelain enameled bars that will last 2-3 years or around $50 for aftermarket stainless steel bars that should last between 6-7 years.
Looking at the three cooking grate options is equally interesting. If you are only planning on keeping your Silver for another couple of years then your choice of cooking grate comes down to cost and personal choice. If you plan on keeping your Silver in your grilling fleet for another decade then the stainless steel grate sure seems like the way to go.
If you have a broken part that is not explicitly listed on the warranty then it never hurts to call Weber customer service (1-800-446-1071) and talk to them about the part you need. I can’t promise you anything but sometimes they do give you spare parts for free or for a small fee.
In 2014 I called Weber about a Genesis 1000 that I salvaged from a trash pile. I told them exactly what I was doing and that I needed some firebox slider rails. They took down my name and address and a week later the slider rails showed up in my mailbox at no cost to me.
Here are the links back to the complete parts lists.
Weber Genesis Silver C Parts