Given the enthusiastic response so far, perhaps it might be worth considering making this into a series of auctions over a longer period -- that way the publicity would accumulate and we could potentially have different charities for different items.
If we put everything up in one go it might dilute the available buying power and get a wide spread of lower bids, rather than higher bids on fewer items.
Just food for thought . . .
If we do make it an auction then what reserve price would donors accept as reasonable? I don't want anyone to end up giving up a day of their time or a bit of expensive kit and only raising a token amount!
Another option would be a raffle, and not close it until sufficient tickets have been bought. I think this would mean a lot more effort and admin hassle though.