Originally Posted by blowinstink
Do I need to obtain some sort of sticker / transponder before I leave? Where do I get that?
The transponder is for trucks crossing the borders to Mexico or Canada regularly. The sticker is for boats and private aircraft. It's cheap (something less than $30) and easy. If you re-enter the US without one they WILL charge you for the sticker fee, but (as I understand it) you won't get a sticker so will have to pay every time.
I got my first sticker--they are annual--in 2006 within about 10 days of the web application. The renewals have been as quick.