I will watch this after Shabbat but will this answer the question of if its ok to be offering Halachic advise and making assumptions that this is like any Chinese auction and by virtue ok to use Massr?
Alot of times the prizes are donated in-kind.
Dan please don't take offense but if by that token one could use Masser without knowing how much is going to the charity then we can all create loopholes, make a blind trust whereof our 10 percent all goes back to us with a small amount going to a charity.
Just like a tx receipt for a dinner that is $360 may say $300 (subtracting the dinner) so to one (I would assume) needs to subtract the cost ... obviously when you donat there is overhead and for a food bank half of your donation can go to salaried employees but when it is something your experiencing for your benefit and not admin costs etc. ( a dinner, contest ect. you should have to subtract).
If your going to be implying that you could use Maser please reveal how much is going to the org.
Please don't take this the wrong way.
Good Shabbat.
So if you win, just ask your LOR how much maaser you should give, as the dollar value of what you receive is greater than what you paid for it.
If you received nothing tangible in exchange, why wouldn't you consider it all maaser (or tzedoko)?
On another note, do you ever *thank* people for soliciting you for a donation? If you haven't, I strongly suggest you start doing it, it will make you feel better about giving, and might also be a form of tzedoko, in making the solicitor feel appreciated.