Go gas!!
Thomas,
I would strongly recommend going with a hanging heater in your garage. If you are not familiar with them, they are available from many different suppliers. Or you could install it yourself. Not that difficult at all. They are available usually in 30K, 45K, 60K, or 75K BTU. With a 30K generally large enough for most two car garages. Unit should cost you about $500. Plus some extra parts, like venting, wire, gas pipe, and a thermostat. I install them for my customers, and it usually costs them about $1200. With everything, including labor. I see you are in Indy, I am just north of Bloomington Normal, IL so our climates are not that different. The cost of operating that electric heater will pretty much stop your building to pay for the electric bill. I looked at Mcmaster Carr, and the small one (17,100BTU) operates at 20.8A @ 240V. Roughly figuring, if you pay $0.10 per kW/Hr, that is roughly $12 a day. Or $360 a month. Now granted that would be operating 24/7, but that small of heater, it will work pretty much consistantly in the winter to keep the garage even remotely warm enough to work in. (in reality, it is not big enough for the job, But would probably keep it from freezing.) Your best bet is a gas fired heater of some sort. Look for a Modine, or ADP (two of the more popular) hanging heaters. They are about the size of a carry-on suitcase, and hang from the ceiling and extend down only about 18 inches. So they take up amost no usable space in your workshop. Look long term at the solution, it will save you money.