Here's a post I'd like you to read about missionaries and money. It's written by Tom Richards at Talking about Tanna who is preparing to go and live and work with his family in Tanna next year.
I've written a lot of my thoughts in the comments, so rather than replicate them here, I provide the link for you to go and read them. I'd love for you to join in the discussion. My comments have been more about "which lifestyle" than money per se but the assumption is that it is more expensive to live a western lifestyle.
It's especially pertinent to us at the moment as our mission agency considers changing the way they support us.