I'm personally not against the spending of money on art projects, and argued that case on the thread last year. However that is a substantial amount of money for a temporary work and I would have thought a permanent work would have been a "better" use of funds.
I got the £20k figure from the 2005 brief which was circulated in Feb - "In the second stage each group will receive £300 to enable them to prepare a suitably detailed submission ... The total artists fee available is £15k. The materials budget is a maximum of £4k". I would have got something more recent from the committee minutes but they've not been updated since April
But yes, I am looking forward to seeing it and taking some shots!