Hire a Realtor who is willing to do Comparative Market Analysis' (CMAs) on properties you are interested in BEFORE you submit your offer. A CMA will give you the current market value of the property and this is what you should base your offer on, not on list price. When your Realtor does the CMA, make sure they use SOLD properties within a 1 mile radius of the property you are interested in and that have SOLD within the last 3 months.
I hope you are working with a real estate agent that is pulling comps for you before you present an offer. In addition, you should speak to your mortgage contact to find out if the appraisal company they are using is local. Some mortgage companies are using appraisers that do not have knowledge of the area and do not present the best appraisals. It's also possible the sellers have overpriced their homes too.