We just paid $2700 to have the outside unit and the inside coil replaced for our 2.5 ton A/C. We left the furnace part alone. 1200sf single floor condo.

Can't compare others to yours, OP. Need to study up and discuss pros and cons of types of systems and put it out for bids. Check Washington Checkbooks for company reputation and cost comparison: best $20 some dollars spent when you're considering new HVAC.