You won't know if it'll make a difference until you know how much you've got, and I for one wouldn't like to make a guess.
If there's a fee, then most downloaders will be put off, or as Smokie says, get around it one way or another. One option may be to make it a printed version, to be posted out to whoever 'buys' it with an online donation, but this would require extra work at the CA end of things. A bit lo-tech, but maybe worth thinking about.
Another scam, which I've already mentioned to Doris in a pm thus:
"While I'm on, one of many areas of confusion to me has been this 'sell a ticket on CA but only at face value' lark. What happens, as no doubt you saw, literally hundreds of people clog the website looking for tickets and a bargain. Usually it's because they couldn't be bothered to order in time and mostly they've never posted on CA before. I know for a fact that many of them re-sell their tix on e-bay after buying on CA. Opportunists if you ask me. May I humbly suggest to you, in your capacity as Charity Fund Raising Officer, that anyone buying tickets at face value from another CA member has to make a donation to one of the charities that you have on your shortlist."
Worth considering?
H