the battery is cheap, a simple 75 amp hour deep cycle at wally world is only 50 bucks or so. wire is pretty cheap too, 100 foot real from maine sails link in another thread is 39 bucks for 18-2 wire here
and if you dont have a panel this panel
would do you boat perfectly. a position for a main, running lights, anchor lights, interior lights, and a bilge pump with a spare.
a simple charger in the house to keep it charged. this would not let you live on the hook but you could get away with an over nighter when you got stuck out. now this is not just a min amount of stuff but stuff that would be nice to have
as for rock fish ummm
edit yes it is worth it, it can give you another hour of sailing most days legally