I have determined that traveling with point to point tickets is the cheapest for my family. I was thinking of ordering a BahnCard 25 to get discounts on my point to point tickets. However on the DB website it doesn't appear to let me order a BahnCard from the US. Does anyone know if there is anyway I order a BahnCard from the US and have it shipped to me before my trip?
I'm not sure if you can buy it from the US, but you should realize that Bahn cards are yearly subscriptions that automatically renew unless you cancel it.
Use your first German address for it. Have it shipped there. Right after ordering it online you get a temporary BahnCard to print out yourself. You can use it for a month after you bought it. The plastic card is usually shipped to your German address a week after you ordered it online. Right after your trip do send out the BahnCard subscription cancellation fax. You'll be fine.
I bought 2 BahnCards in 2010 and had them mailed to me in Canada. No problems at all. Then I did as Andreas suggests and faxed the cancellation letter immediately. They acknowledged the cancellation with a letter. The cards were valid until the end of the period (I bought the 4-month ones), then the cancellation took effect and I never had an issue.