According to the description of this product, the seller indicates that the cross bars are made of aluminum which are silver in color, naturally. He also indicates a 3 year warranty. Of course, the warranty and a dollar will get you a cup of coffee.
The very first thing you must do is ask the seller if the bars are painted or anodized. This is part of the process of self protection.
You have protection being an ebay purchaser. If the product turns out to be misrepresented, you are entitled to get your money back including the cost to ship the product back to the seller.
If I was you, I would not be afraid to get them if silver is your choice. Just be sure to check them out very carefully when you receive them and act quickly if there is a problem. You can always do a small scrape test on them to see if the finish is paint or anodizing.
I have been selling and purchasing from ebay for more than 20 years. In fact, I purchased my rails and cross bars from ebay and am more than satisfied with the quality. I also saved a huge bundle of cash by avoiding OEM pricing.