Good Decision - Just a quick point on Backpackers comment though;
And if you're worried about the legal issue: No, as long as you only accept money towards a fair share of the flying costs
The "fair share" rule was done away with not long ago I believe, along with the whole flight must not be advertised thing, and your passengers can legally pay for the entire cost of the flight as long as you don't profit from it.
ES
Source: IN-2014/093