Hi, ask your Realtor for a CMA, that will be a great offer price since the lien holder will do almost the same.
Maybe some dollars off the CMA estimate sales price. If seller did a CMA, the current price is a reasonable price.
City assesments values are off the market.
If you offer is very low, it might get rejected and you will need to restard the process again with a new price.
If you offer listing price, it could be approved and go to closing. Also, a good offer most probably will get tisgned by seller. Short Sale Seller could denied the signature of a "bad" offer.