Here's a 2 ton system at Home Depot you can buy tomorrow for $1899. That's would probably make a wholesale price around $1000 to $1200. Seems like $3600 for your old system removed and replaced with a new system seems right. In 2011 I paid $3500 for a 2-1/2 ton Carrier system installed in my home in Baltimore.
Winchester 2 Ton 13 SEER Sweat A/C System with 17.5 in. Coil and 30 ft. Line Set-4RAC24S17-30 at The Home Depot