Since no one else seems to want to actually answer your question, here is another option.
From Home Depot. I actually have 2 of these stands for setting mixers on or even my small moving heads. I just add a simple black drape over them. And of course you can also sit them on subs at some point if need be. Sure centering the subs would be better but clearly that is not always feasible. While a 2x15" may not be the best speaker design in the world, it can get the job done. No matter what speaker you have someone will always find a flaw in it.