A couple of important parameters:
-how closely does the temperature have to be regulated? The 120 - 150
is the range, I assume, that you want to be able to set it in, not the
allowable swing. Or not?

- is this for commercial/industrial use? I.e., needed for extended,
trouble-free, use. Or for occasional home use?

The electric stove-top element Ned mentioned is around the right
wattage, IIRC. Also compact.

For cheap, not-too-accurate, regulation I would probably go with an
op-amp based circuit. Thermistor as a sensor, drive a MOSFET that
controls a relay that switches the AC power to the heater. Google "op
amp thermistor thermostat".

My intuition is that 150F is not that hot for a fan. But convection
ovens use fans that circulate 500F air.

HTH,
Bob