When we look at all the free, DIY learning that is out there now, it's free precisely because it hasn't been commodified. You can download stuff from MIT's Open Courseware because that kind of learning has no commerical value. If you want to get a badge though, that's going to cost. All the big textbook publishers and educational technology companies will just jump right on badges. All those Sylvan learning type companies will be selling badges. Edutainment video games and such will come with badges and thus be more expensive.
Badges won't make learning cheaper. We'll be spending more money on education than ever, and we won't get any better results because the motives for learning will still be all wrong.