As a certified Residential Appraiser I will tell you that price per square foot is a weak negotiating tool. Appraisers will use this type of adjustment for valuation purposes, but you should understand how it evolves. The final price/sf results from dividing total square footage of the living space (above grade) into the sale price. The sale price is the result of negotiations based upon location, condition, room count, amenities, etc. If the comps are showing lower price/sf, maybe there are reasons for that which you should analyze with your buyer agent.
If you need additional help with this, you can contact me.
Carol Murray Cei