Since you are asking for fees when a user creates a contest, you should provide case-studies of savings on similar flight searches in the past (also include cos

Since you are asking for fees when a user creates a contest, you should provide case-studies of savings on similar flight searches in the past (also include cost-benefits over other flight search engines). May be, even allow the user to extend the contest duration (with some constraints). Doing this should give a better assurance to the user. I believe your service has the potential to do well in this market, particularly considering there are many variables involved in flight searches.