Holts has a nice single cigar all aluminum ashtray for under 10 bucks. It may not be what you are looking for since it isn't flat, but it's light weight and strong enough to take a beating. I have one and use it for robusto/corona size cigars, but anything larger and you will need to dump the ashs mid-way through.
http://www.holts.com/category.html?id=86670
Good luck.