Listen to stickandrudderman - don't pay large amounts of money up front. This forum is littered with students who have lost money doing this.
In the case of Ravenair, there are two companies with this general name of which one appears to be technically insolvent according to its last filed accounts. It also does not display its correct company details on its web site and so breaches the Companies Act. Be very certain who exactly you are paying if you go ahead with this as this will determin who you have your agreement with.