Function to grab info in middle of string

[DKY]

I want to put together a function that grabs the 23.85 out of a string like this

$23.85@74%11-14-07

or the 353.67 out of a string like this

$353.67@42.9%11-14-07

but haven't the slightest idea how to program the logic that would grab that out of a string. Can someone give me some direction?