Here's one that is a nice set:
Cooling System Tools Astro 7858 Astro Pneumatic 7858 - Universal Radiator Pressure Tester
The key with these, is that there are many different sized radiator caps...so you need the right adapter for your car. AST (Assenmacher Specialty Tools), is well know for making good quality adapters, and you could buy just the one you need, (they run about $50 ea.). Both Stant and Snap-on sell the pump/gauge thing with only one or two basic adapters. Blue point sells a set of adapters. But the set referenced above does appear to be pretty complete, and is the one I used to test mine, (it came off a MAC Truck).
Here's the Snap-on version:
Pump:
SVTS262C, Tester, Cooling System
Adapters:
SVTA17000, Set, Cooling System Adaptors, 17 pcs.
Just the adapter for BMW:
TAB10345, Adaptor, Radiator, (for SVTS262B Cooling Tester)
As you can see, the adapters can get VERY costly. And the above Snap-on one's are metal/plastic. The AST are all aluminum, and a bit nicer. Both USA made. The first set linked are all metal as well, and pretty nice IMO, but totally Chicom.
Another reason to test the system cold is that sometimes it will only leak cold....
Pump the system up to about 15lbs, and leaks should show up. Except if it's leaking into a cylinder. Mine was pretty much holding pressure, but a slight defect in a hose showed up as a VERY small dribble from a connection point. If the system does not hold pressure, and there's no sign of leaks, time to pull the intake. Assuming there's no sign of smoke in the exhaust. There are ways to test for bad head gaskets, (chemically test for cross contamination of oil to water), such as this:
GDCT16, Tester, Combustion Leak
As tight as the V8 cars are in the area near the firewall, a fibre-optic camera is not a bad tool to have on hand as well; not to mention a lift.