Hey,
I coached an international team (4928) in the UAE and we had the same dilemma. A few things that we found out...
1) The batteries that FIRST has for international teams all got shipped to the location with the field. For our first year, we were the only international team at our event so although we had only been promised 2 batteries, there were actually 6 (maybe 8?) available to us. It was great to have extras! Some of them were on the older sided and didn't hold the full charge. So, check the number of international teams registered for your regional event.
2) We had an awesome mentoring team (LiveWire 3562) that was attending the same regional as us. And they were driving there, so things like heavy/bulky power tools were easy for them to bring and share. I'd highly recommend sending an email to some of the established teams attending your Regional if you don't find someone through this thread. It was also great to Skype them all Build Season and then meet up face to face at the Regional! If you can't find someone who can promise you good batteries, I recommend buying some locally once you get stateside. Where cost is an issue you can always try to find a team who will buy them from you after the Regional? But again, if you find a mentoring team close enough to drive, they might be able to transport the batteries to Championships should you qualify, or hang on to them for next year if you think you'll return to the same Regional?
3) This idea doesn't help you for now but our second year it worked to have a team mentor who was visiting stateside pick up our kit. He left the batteries with family who then drove them to the regional we were attending. Excess baggage fees were still much less than full KOP shipping to our team's location.
Good luck and if you need anything, just ask - FIRST is full of people and teams that want to help you have an awesome experience!
