80€ for Makita and 40€ for no-name brand. They've been tested and the 5Ah rating is accurate. What's remains to be seen is how these last long term.
I bought a pair of 6 ah off brand makita batteries about a year ago, mostly to use in the kids power wheels instead of my good ones. They're still kicking I'm pretty impressed. I might have gotten lucky though, part of the lower cost is less quality assurance I imagine, so more of a dice roll to get decent ones.