The main question here is: how much utility would you like to get out of your experimental unit? Will it be compact or spread out? Recirculation of hot water through the condenser or heating cool water? Indoors outdoors, or both? High pressure cutout or thermal cutout? All these questions will bear directly on your condenser specs.
Here is today's deal:
Surplus City Liquidators
Swep has an app that will model your conditions and tell you exactly how much heat the model in question will move. Go fish.