Brian --

Sorry to hear about your lost balls... you'll find 'em again come spring...
Yes -- I heat the shop with just the fluorescent lights... they are High Output T12's - 120w per bulb - two per fixture - 16 fixtures... on 24/7 once the weather gets cold enough to need it.
Now -- it was down to 20 degrees here all last week - so the shop (I was gone) dropped 10 degrees, down from 71 as measured with infrared on the tool boxes to 60. So I "added" some heat from my Grainger 220V 5000W heater - but have since turned that off now that it's climbed back to normal outside temps (like low 40's).
I have - what I would describe as MAJOR - insulation... and have been continually amazed at how cool it stays in summer - and how toasty in the winter.