according to the tax laws you are allowed to claim the cost of materials (pattern everything included) so i would say go ahead and start it at $100 but can you put a minimum on it? if so the $250 you have into it would be appropriate. the thing about auctions is if you start high no one bids, there is a better chance of getting a good price if it starts low enough to get bidding started. i had one once that i had $200 into... it was to be raffled...the group did n't (bother) very much with selling tickets...they made $45 on it...i was so ticked i have refused to ever make them another one...but i had one that sold for $1800 so you just never know...but the rule really is, once you donate it...it's not yours anymore, so what ever they do with it is their gain (or loss) you get to claim the $250 you put into it on your taxes (if you itemize)