https://www.amazon.com/dp/B000G1CXZI/
I bought this one from Amazon for $71. It's not on wheels, but it's very compact, lightweight and easy to move, yet doesn't tip over. Heats very evenly. Only challenge has been figuring out where to turn the dial for the correct heat -- but a few tweaks and I had it.
It has a timer.
I thought it was important that it has a manual on/off switch -- not a digital. So if the power goes out, and then comes back on again, it will come on.
I'm using I in my 6 x 8 greenhouse and it can put out way more heat than I need. Its not specifically rated for "outdoor", but no water gets into my GH, and I think the cord has one of those ground fault things built in - so I think it's okay.
