My wife works in construction and I used to give her a new Thomas Guide every year for Christmas to get the latest updates. It was kind of a joke though, because even in the best scenario this year's new guide only had the roads and projects she built last year and it couldn't ever have this year's projects because she hadn't built them yet.
For something like a road atlas though, my feeling is that something like that is kind of a dying product and if I want to continue to use it, I'd better be prepared to support it and pay up every year.
In my truck, I pay for the updated NAV data usually once a year or every 18 months.
Honestly though, there isn't a huge risk to having slightly outdated maps. It's rare that roads are deleted; it's just new roads being added. So if you don't have the latest info, you'll probably just miss a shorter route but not drive off a cliff where a road was deleted.