We have a minimum bid of 10% with bid increments of $5, so we round up to the nearest 5. Sometimes it depends on the item. 10% of an item's worth may be way too much or way too little sometimes.

The average item in a silent auction brings about 30 to 40% of its value. (Sources - several auction sites and members of this forum.)
I have seen auctions list 10 - 25% of the value as the minumum bid. Some went as high as 30% but then got very few bids. You may check ebay to see what things sell well when deciding.

This year we're having 7 baskets full of goodies for a Silent Auction at our Carnival in two weeks. If a basket is valued at $50.00 what should the minimum starting bid be and what should we expect to get for a $50.00 basket?