I installed this little 220v heater in my garage about 9-10 years ago, and it's still going strong.
IIRC it was a little less than $100, and has a thermostatically controlled heat setting. Although before the install I had to change the plug over to a standard 50A version that I use on all my 220 tools.
I decided to hang it up off the ground and fabbed a bracket out of some scrap stock
Hung up and ready to go to work --
On really cold days it can get my 680sf garage from freezing temps into the mid/high 50's in just about 30-40 minutes. The floor is still cold, but working height with the car on a scissor lift is very comfortable.
Since my garage is attached to the family room via a small laundry room, if I need immediate or extra heat, I usually load up the wood stove in the family room and the heat flows directly into the garage.
Between the two heat sources I'm usually very comfortable working in the garage in all but the the coldest winter temps.
I can highly recommend these little 220v electric units -- very portable and efficient.