hey, that's my hobby !

there are no RTR RC kits on the market.
as fas as I know, there is a RTR toy from Graupner,
another from Nikko, and a few motorized kits
from Academy. none is an VII-a
I seem to remember academy having a VII-c,
although barely recognizable
In my view, for a kitbuilder it is perhaps interesting
to R/C the Revell VIIc (1/72) as a surface runner
(no diving...). two motors and a rudder and voila !
otherwise, visit and learn from
http://www.subcommittee.com the average "kit" built there is about 1000,- usd.
might not be what you are after...