Hi

The Amazon ones that come for < $20 with the heatsink seem to work fine. The one I have is a 100A version. It was still dirt cheap. The relay and heatsink never seem to get hot. You can drive them with just about any signal off of the Ramps. Configuration wise, it is *much* easier to just hook them to the same output as the "gizmo" normally uses. Marlin is configurable enough that there are a number of other options....