Under $3k, Vectorworks Landmark - almost all of the Mac-based LAs I work with use this app package. I prefer Landmark over AutoCAD (which we also use) with LandFX and/or Keyscape running in the AutoCAD environment.
An alternative is Graphsoft's ArchiCAD WITH the Rik Landscape Pack - keep in mind that ArchiCAD 20 is hitting the streets soon, so pony up for v. 19 only if you have a clear path to a free upgrade...
If you need 2D only, 2D DWG compatibility, and decent editing tools look no further than Dassault Systemes' DRAFTSIGHT. DRAFTSIGHT offers a free version and a "Professional" version, and both versions are regularly updated; the Pro version is currently offering a reduced subscription price (I got the email...) from $299 to $99. IMHO DRAFTSIGHT blows AutoCAD LT back to the stone age...
