There are some nerdy details about the differences between the Muscle and Neuron SpikerBox. Both can record ONLY one channel, but the purpose is completely different.
The Muscle SB has three leads for differential amplification and wider filters, but yes, in rare times it can record from neurons in the cockroach leg. If the budget is tight you could pull this off.
But we recommend buying both, the Neuron and Muscle SpikerBox, as the Neuron SpikerBox is optimized for insect experiments with included electrodes, and the Muscle SpikerBox is optimized for human experiments.