If BTC is not work for you:
If the money is for yourself, just use a credit card that doesn't have foreign transaction fees.
If the money is for someone else, I would use PayPal or Western Union or something else like that.
I haven't seen a credit card that allows up to 50,000 in limits. Are these actually available?
I would imagine the cheapest would definitely be bitcoin, but purchasing bitcoin will still have some exchange fees. So the next best option is probably a wire transfer.