Eden pure heaters?
Save yourself money now and long term and get this simple propane unit:
http://www.lowes.com/pd_37481-46631...L=?Ns=p_product_qty_sales_dollar|1&facetInfo=
Puts out tremendous heat. Way too big so I run it on low and turn it off alot. I run a fan to stir the heat around the shop. It converts all your propane to heat in your shop. It does not vent any heat outside. It does create a very minimal amount of exhaust which is clear and clean but is co2 and co and h2o. This means you need to let fresh air in the shop occasionally. I open the pedestrian door once every few hours for a few minutes. Or have a window open a bit.
80K btu max on this one
120 bucks and also they have a larger one. Cheapest heat you can buy.
I hooked a bbq propane tank to it. Toasts me out in 10 minutes on high when it was 30 degrees in my shop. My shop is 400 sq ft so not big at all. This would work for a considerably larger shop I am sure. It is pretty quiet also.
Electric heat is not efficient in cost compared to propane. BTU vs. $
My opinion :)