What do you mean?
They sell generic grill covers at any hardware, home improvement center or discount store like Wal-Mart, Target, etc. Or you can just purchase a plastic tarp and hold it together with bungee cords.
Buy a grill cover?
Is this an outdoor grill?
You can buy a grill cover from many stores or Amazon, usually they are enclosed when you buy a grill.
For the diy'er in you:
hometalk has this idea!
We just have a black grill cover. Ours came with it. Could you look up your brand and order one? Amazno usually has generic cheaper versions too!
Some of them have covers included. Or you can make your own - here's a step-by-step guide.
Here's the topic where gents are discussing custom made ones.
But honestly, I have one of the Weber spirit series grills (like the one on the list) and bought a extra special brand-made cover as it wasn't included in the package.
For a long time I was perplexed with why it had so many mesh slits in it, which would obviously allow water to come into the cover. I then researched and found that rain is really not the purpose of the cover, but more so to protect from falling debri and the sun.
At any rate, I am super lazy and usually leave the cover off and the grill has been fine for 5 years. So I don't believe it's really that necessary, but for each is own. Just my two cents.