from herbert gintis, re a tilde in text:
I often use something like this: 200\lower3pt\hbox{\~\
}\kern-2pt300. The tilde is a little too narrow, but it'll do.
If you don't mind going into math mode (why should you?), this is
fine: $200\kern-2pt\sim\kern-2pt300$.
this is equivelent to the latter, removing the space
placed around a relation:
$200{\sim}300$
-- bb