There is an easier way. You can use the norm
command. I would recommend this:
Visually select all of the lines
Type
:norm I"<C-v><esc>$i"<cr>
When you actually type this (before hitting enter), the text that should be shown in your command line is:
:'<,'>norm I"^[$i"
The norm command tells vim to simulate a set of normal mode keystrokes on certain lines. In this case, the command is:
:'<,'> " On every line in the visual selection:
norm " Do the following as if typed in normal mode:
I"<esc>$i" " Insert an '"', escape, then insert a '"' at the end (before the comma)
You can also do this without using a visual selection, by typing <n>:norm ...
, and the command will apply the current n lines. (the current line and the next n-1 lines)