We present a design for an olfactometer, suitable for fMRI experiments, that can be constructed at extremely low cost. The olfactometer presents odors directly to the nose via a nasal cannula at unobtrusively low flow velocities, with no large assemblies required on or near the subject's face. The olfactometer can be controlled manually, or by computer via a serial interface. A validation study verified that the olfactometer reliably presents odors to test subjects. Errors and response latency times decreased with increased flow rate in an orderly manner, as expected.