Hi Sharna,
I have been organising a raffle for racefor life too and so far have had some good prizes donated through simply e-mailing local stores and T.V shows! On most on-line store sites you will find a contact us link at the bottom of the page simply click on it and e-mail a request for a donation to charity. So far I have had replies from Woolworths, Peacocks, Ipswich Town F.C , GMTV and Coronation street!, amongst others. Try local restaurants and pubs too as they may donate a free meal or drinks. I found it easier to include a postal address in the e-mail and then you may get a lovely surprise on your doorstep. Good luck and remember if you don't ask you don't get!
Good luck with your race too -sue-x-