Looks like they don't have the new model, the A1 Solar Lantern, on Amazon yet. The one for $47.95 is bigger (16 hours of light instead of 4 hours) and has a USB charger to charge a phone.
Regardless, $5 seems doable. Rechargeable batteries are cheap. LED lights are dirt cheap. Solar panels are pricey, but I see some 1W ones for under $5 on Amazon, which means they probably cost $1-2 in bulk.
Given that, around here anyway, solar powered "night lights" for use outdoors are very prevalent and only set you back about a dollar a piece... $5 certainly seems very possible.
Now these lights I'm talking about are really quite dim (and omni-directional), but they really are disgustingly cheap as well.
A product designed to be of practical use rather than almost purely for decoration, and at 5x the price point, would most likely fare a lot better.
Edit: Would "likely" fare better? Obviously it does. I seem to have lost track of the point I was trying to make, namely the price. XD
[1] http://www.amazon.com/d-light-Rechargeable-S300-Lantern-Char...
[2] http://www.amazon.com/d-light/b/ref=bl_dp_s_web_3023737011?i...