Propane catalytic heaters are safe to use indoors. Propane inherently produces very low amounts of CO and when there is no flame IE catalytic almost none. So a drafty garage door is sufficient ventilation. I have the mid sized buddy heater I use for camping either in my camper or tent and it goes all weekend long on one pound of propane. A 20 pound bottle of weekend wrenching would last you almost two months.

who sells the heatdish? couldn't find it at costco anymore.

So that one works well? I was looking at it a while ago, but decided against it for no good reason. Maybe I'll go pick one up while it's on sale!

Hmmm...which one's more energy efficient?

I still have to seal my doors nice and tight though.

Those of you suggesting thick/thermal clothing, being able to work in your garage in a tshirt in the winter when you're in there a lot is great. I'd rather not have to bundle up every time I want to work on my bike/car.

My garage is bigger than yours with zero insulation and two small floor heaters from walmart heat the whole thing up in about 15mins and I usually have to turn one of them off.

You'll warm up a lot quicker with NO draft...

Saw some at XS Cargo... 800W, $30. No idea how durable they are, but should warm ya up quick for cheap.