Fusion using deuterium is one of the easiest nuclear reactions to perform. You need a small bottle of D2 gas, a vacuum system, a specially configured chamber and a modest high voltage power supply. Fusion devices are widely used in elemental analyis, oil well logging, etc. Here we're not talking about fusion power generators, just simple vacuum tubes that produce neutrons. That said, putting together such an apparatus requires time, skill and patience. Measuring the neutron output is another challenge. Read all about fusors here: http://fusor.net/
D2 gas? Do you think Safeway would carry that?