The first and most major part of getting to Wacken is the finances. The ticket is going to cost you 100 euros after everything is added in: camping fee, Metaltix's service charge, etc. This is going to work out to about $130, but will include your accomodations, so it's going to be significantly cheaper than going to a multi-day festival in the US and paying for several hotel nights. However, the killer is airfare. No matter how you cut it, getting a flight in to Hamburg is going to run you about $1000. Experienced travelers might be able to get a flight into one of the other major cities in north-west Germany and then get over on the Deutsche Bahn, but if you don't speak German, it's best to minimize your time in the German rail system, and the costs will probably come out pretty similar. Book your flight well in advance, and you'll save a little bit of money, but the best way to handle this is just to budget well. A good time at Wacken, counting flights, ticket, food, beer, and merch, is going to run in the neighborhood of $1500, which is a stiff bill for most metalheads, but usually manageable. Remember, you've got a year to save up, and there'll be a few little tricks later on to save money at the festival.
The second important part of finances is on-site cash. DO NOT bring US money over and try to convert it. The dollar is critically weak with regard to the euro, and "assraping" is too kind to describe the shenanigans that go on at the exchange counters. If you've got an ATM card that's on one of the major ATM networks, it'll work just fine in Germany, and most ATMs, including those in the village of Wacken itself, have the option to display instructions in English. This way, you pay only your normal transaction fee instead of getting screwed out of 10-15 percent of your beer and merch money. Be sure to check with your bank on your daily overseas withdrawal limit before you go over: this will determine how much cash you're able to have on hand. If you try to withdraw more than this on any single transaction, the ATM will complain, and you will neither get any cash on that transaction OR for the rest of the day. This can ROYALLY fuck you up, so take care. I got messed up by this when I was trying to pile up the cash to make my apartment deposit, and I had to sleep on the floor at the office for a couple days before I got the cash together.