I think that most of the people who are pre - ordering represent the most fanatical fans. there will be more than likely a lot of people holding back in fear of not receiving a game that will live up to their expectations or indeed that you will fold before the game reaches completion. my hat comes off to those who were the first to pre -order, with surely only your promise that their investment would one day reach fruition and to you guys for getting this far. As for me, I only found out about this game while seeing a random comment on the facebook xcom page a few days back and after seeing the video and seeing you guys are in the uk am willing to go premium, I can only hope more of the scroogy skeptics realize its not going to be a good game without our pre orders.
As for ideas to further ideas to rattle our money boxes, maybe offer the game on disk on its completion, Easter eggs like signs with the persons name on in game.
alternatively I would have thought there are government grants? and also surely more advertising would lead to more sales I would have contacted the people who are releasing the new jagged alliance to see if you can put a flyer in every game sold?