Dando does look lovely.
If it were me Annoca.. I would just say yes on Thursday (even if I hadn't quite managed to secure all the money)... I know this is irresponsible, but I know that it is what I would do in your position... I would then continue to scrimp, beg, borrow, sell anything I could on ebay (relatively easy to do from home, only need to get to the post office to send stuff) etc.
When will YOU have to actually hand over the money. Is someone covering these costs somewhere, and you then have to reimburse them?
I am not saying don't pay them, obviously... but if I was still waiting to rake in the full amount, I would just be sending them as much as I could, every time I got my hands on it.