KABusa.com sells the least costly, non-DIY vacuum RCM out there AFAIK. It's basically a Nitty Gritty without a built in vacuum, you hook up any home vacuum cleaner to it. Other than DIY it doesn't get any cheaper than that (assuming your home already has a vacuum cleaner of course!)
I haven't used or even seen one, so this is not a recommendation other than to take a look.
I haven't used or even seen one, so this is not a recommendation other than to take a look.