Is this 200 yards through buildings or pretty much line of sight? If it's line of sight, then you should be able to get away with a strong wireless access point at your end, and a strong receiver at hers. It's pushing it, but should be do-able.
If it's not a direct line of sight then it's not really possible (well, it is, but the expense mounts up so quickly it doesn't tend to be worth it.)