Maybe the high figure is what he told his wife??

Gary Evans wrote:
My DG808B self-launcher uses 4 sealed batteries and
they all can be replaced for less than $80 which I
believe is typical. The batteries are cheap enough
that I replace them every two years regardless of condition.
There is no gas powered glider that I know of with
a $1000 battery but perhaps an electric self-launcher
battery could be that expensive.
Reliability and maintenance on any powered glider is
going to be significantly more of an issue than a pure
glider. It isn't like buying a Chevrolet where the
various systems have been refined over a long period
of time. The fuel/electrical systems used today are
pretty crude compared to modern automotive design but
given enough attention and preventive maintenance they
perform pretty well. Routine operation is a very good
idea regardless if it’s a self-launcher or sustainer.
With the exception of one loss of electrical power
mine has never failed to start or in flight after 325
frame and 25 engine hours. In that same period I have
experienced 4 rope breaks on tow so the self-launcher
reliability looks pretty good to me.