The current Kenmore Elite covers are pretty nice. I have the 56" x 25" x 44" one for a Silver B and it's made from a water-resistant fabric.
It's a little tall so the it covers the entire grill down to the wheels and then some, so it's not the best fit, but it has some nice features like handles that are sewn on and built-in vents so that it doesn't get blown off.
$50 is the regular price, it's often on sale for $40 or lower.