I can see Mark's logic though.
I totally understand that you want to keep it as a community, not a business, but you could have everything as it is, but rather than 'just a donation', you buy stickers/whatever for a donation - ie. donate up to £X and get stickers, up to £3X and you get...
People always like to get something for their money - hence the pens from Cancer Research, or the 3 disgustings sweets for 60P or whatever!
(I've never looked in this section before, so I'm possibly repeating everybody else's thoughts - if so, sorry
)