Sale contingencies are not common in Madison right now unless it 's contingent upon a "successful closing" vs a "successful sale and closing". Most folks with homes to sell will wait until they have an accepted offer on their existing home before moving forward with a serious new home search. In the event they don't find the right home to buy, most are open to living in temporary housing while they continue their search.
If you have zeroed in on the right home for you, and do not want or can't assume bridge financing I would have your buyers agent learn more about the seller's motivation and moving timeline. If they have flexibility and your home is currently being marketed, the seller may be more amenable to consider a sale contingency.
Please provide additional details if we haven't fully answered your question.
To answer your question we closed on 40 transactions in 2008 and only 2 had a home sale contingency. If the home in question has been marketed and is aggressively priced there is a little more leniency as opposed to a home that is not currently marketed and is not priced to sell in 60 days. Sellers do not like to see a closing date much more than 60 days out and therefore the motivation to sell, if this is "your" home, would be much greater.
On the flip side the seller could also offer closing costs to accommodate your holding costs and therefore you may not need to have the contingency in at all. Without knowing the specifics......hard to say what would be the best way to deal with it. Call me.