Just because it is a short sale has nothing to do with the price. The short sale just means that the person selling it is selling it for less than what they owe on it. Potentially a short sale could have a higher price than comps in the area simply for the above reason.
The first step is to make sure that the agent representing you is an expert in short sale contracts . The majority of all short sale offers fail to close because the agents on either side of the deal lacked the training and the experience to successfully negotiate the deal. It also fair for you to have your agent inquire about the listing agents training and experience in this area.
Most of the time lending institutions will hire real estate agents to perform a BPO ( Broker Priced Opinion) to determine the value of a property. The problem is that most of the time these are drive by BPOs. The agent is paid between 50 and 100 dollars to drive by take a couple of pictures the compare it to other sold properties and competitive properties ( homes currently for sale). The secret is to control the BPO. An experienced Short Sale agent will complete their own BPO that includes an inspection of the interior and an estimated list of repairs that are needed and come up with a estimated value in the current market.
It is my experience that most lenders are looking to get 90% of the BPO. After costs and realtor fees this means the bank is taking between 18 and 20 % loss on the current market value.
Lastly make sure that you can prove to the lender you are ready to move fast and have the ability (money) to close this deal before they lose any more of their investors money. Another way to grab their attention is use the current lender for your financing. This makes it a win win for the bank.