I would try to heat the whole garage. I have a stand up oscalation heater I used for my living room this winter. It has a remote, and built in thermostat. I love it, and it was only like $75. I also have an oil filled heater that was only $30, but you might need two depending on the size of the garage.

You can use heat lamps, but if there is a draft or any type of air movement, the heat lamps might not work. Good luck.