Read EVERYTHING carefully and you will be OK. Remember, if you cancel you normally do not get any type of refund.
I think almost all auctions have a tax type fee. Most week long stays are something like 249.00 + 20.00.
Some will have a bid price per NIGHT. Often these will have a 32.00 per night fee.
Watch your available stay dates carefully. On the per night stays watch for blackout dates or dates that have increased fees.
Some auctions, especially those with airfare included, are per person for a family of four...so that is actually 4 times the price you bid. I believe that you must pay for at least 4 people on these and it is normally two adults and two children. (I have never bid on one of these so double check for yourself.)
Pretty much forget busy times of the year for availability, or expect lesser accommodations.
The
very best deals are normally last minute deals for travel "next week" dates. These deals can be unbelievable! If you can drive on short notice you can get some
fantastic deals and offers from resorts that I only see appear when the stay date is very near. Of course if you have to book airfare at the last moment the increased airfare cost can wipe out or exceed any sky auction savings.
The have airfare only auctions too, but I can normally do better myself when I have checked.
If you are gutsy and you will be traveling in
off season you could book airfare way in advance and wait till about two or three weeks before travel to find a skyauction room, but I am not a big enough risk taker to do that. Don't even think of doing that if you want to go during normal vacation times when schools are out.
The timeshares are usually not the most popular ones in the area (duh) and the rooms you get can be the less popular rooms... think pre-refurb room or less desirable location within the resort. Still I have gotten some nice rooms. (but don't count on it and you will be happier with what you get.)
10 years ago fewer people seemed to know about it and the choices/deals seemed a little better. ( So I don't go around telling everyone I know.

) I also suspect some timeshares dropped out because the salesmen were being told " why should I buy into your timeshare when I can rent from skyauction so much cheaper?"

So if you decide to do a timeshare tour somewhere someday, don't say that!
Interestingly enough, I have found some really good deals going on during September when Disney is doing free dinning. If you are going at that time and you don't want free dinning or to stay on site, this is a great time to pick up a good Orlando area timeshare.
One last thought. I have never seen it posted on the auction site, but I had a resort person tell me once that some resorts only allow you to travel on the S.A. certificate to their resort once every X number of years. If you are thinking about returning to the same resort the following year, you might want to ask
the resort if they have this limitation.
EDIT: the limit on returning may be really be an issue, see the post below this one.
Good luck.