One of my test setups:

This test setup costs about 10$ including programmer and all components.

You don’t need FETs and AMCs for testing, power LEDs would be too bright for longer testing anyway. Use simple 5mm or 3mm LEDs, one for each channel, connected to the MCUs output port with a resistor between. Much better for fine tuning and detecting bugs.
Many MCUs are available in DIL casings which you can fix on the breadboard without any adapter. There a adapter boards for surface mount versions of MCUs available at OSHPARK, made for a dollar or two.
A scope is helpful indeed, but frequencies can also be measured with most multimeters. A multimeter is required for sure.