AC/Heater for the Garage... HELP!

[Fishman]

I need a suggestion on what to get for the garage. I was looking at buying a window AC unit this week (14,700 BTU's)... and then I would purchase a heater later in the year. I have been out on the www and found that they now sell a dual use, portable unit that is both an AC and heater. I have a 500 sq ft garage and the garage door is insulated. I have a window for mounting a unit in, but would prefer a free-standing or portable unit. That way, I could just open the window for fresh air when needed. This would not be used 24 x 7... just on days when I choose to do something in the garage.

I am looking at spending under $1,000. Any suggestions would be GREATLY appreciated!