Another thing to consider is the overall audience for the event. For example, if you have a really large audience, you may want to consider the raffle route with the idea being that there might be be smaller increments of sales, but in greater numbers. One way to take this into consideration would be to take a look at the value of the items and just assume you sell each for 80% of the retail price (better to be safe than sorry). Compare that amount to what you might guesstimate you could sell in raffle tickets. I am in agreement with Ninja4Good, though. In my experience, auctions have done very well.
PS - Our school did an auction where we also sold hand painted (by the students) wine glasses (which came with 1 glass of wine). Not only did we make some pretty good money, but it put people in the "bidding mood" during the auction. Good luck and I hope that helps!
Rose is absolutely right. Many factors come into play when determining which type of fundraiser to hold, raffle or auction. But during my many years of experience doing various fundraisers and events I have found that auctions do raise much more than raffles. The exception would be if the item being raffled off is a car or home. But why not hold both at an event? They both can be highly profitable and add a lot to your event.
This is a great question, SPPTO! I'm thinking various factors come into play, including the school community likes and dislikes, the number of total fundraisers you have in a year, and the type of event you'll be hosting for the auction.
It would be great to hear what members of the community have to say!
I can imagine bidders being deterred from participating in a Silent Auction if the price gets too high. But everyone has a chance in a Raffle. However, I have never done this before, so my opinions are void. Do you have any insight?
Good luck and I hope that helps! 
