DizD
I have similar sized shop (500 sq ft) with this unit. Best thing I've done. I keep it on low(50 deg) all winter - it will heat shop to mid 60's in 15 minutes or so. But the absolute best thing was, I found it on closeout shelf at Northern during the spring - marked down to $75. I think you have to balance cost of elec with convenience. If your shop time is irregular like mine, being able to go work for an hour or so when you want without having to do anything but turn the dial for heat is worthwhile.