I'm worried by the variables here. It's seems to be an NP-complete problem:

• €y from the budget for sponsorship.
• x people get offered sponsorship.
• k (where k < x) people are willing to share a room.
• m (where m < x) people are travelling from a great distance.

How do we solve this equation? People want to know if they're being sponsored or not: take each case on its merit as we see it (order of request) and stop when the budget is exceeded? However, that may reject people and then we have budget left over. But we still don't know how much the travel will be, so we don't know how many people to approve. Do we just try to minimise m?

Quim: excluding accomodation, can you say what the average travel bill was for each sponsored participant last year? That at least will help hone in on x.