Already up $100 over retail. People are nuts - ship time on these is what, March 19 now, 3 days after release? I can't imagine paying $100+ to get one 3 days earlier (if that's even the case after it is shipped to you and then shipped to them - it'll probably be like 1 day difference).
That said, I wouldn't be complaining if I were in your shoes! I should have preordered one too apparently...
That's just for the United States. Some countries already have a 2-3 week backorder, but there are a lot of countries whose launch dates haven't even been announced. And last year the US backorder got up to 5 weeks.
I've never sold an iPad to someone in the United States. It always goes to a buyer in another country where it wasn't yet for sale.