I just noticed that /var and /set can't take "" as a value since it will be taken to mean an empty string. I'd like to see /set's -n switch (and /var's too if my other suggestion is implemented) treat it as ordinary text.

Use $chr(34) $+ $chr(34)
That will give you ""

Nope, the behaviour is at the parameter level, not the parser level, so no amount of tricks will help. Actually the variable probably could be filled using $regsub(), but it's ridiculous to have to go to that trouble just to set a variable.