Let me say first that I live near Houston, TX and winters here are not really winter like I grew up with in MI. However the high humidity makes it feel colder than it is and goes right to my old bones.
In December I used the central heat with the unused rooms shut off. Due to dead animal smells coming up the vents (read about that here) I did not use the central heat for January. Instead I used the 2 ceramic heaters.
Both of mine have 3 settings, cool which seems pointless to me, warm and high. Mostly warm is good as I am not trying to heat a huge area. My bedroom is roughly 16' x 12" and one of these on high for 2 hours makes it toasty warm enough to either cut it back to warm or what I mostly did which was to turn it off and sleep under my quilt. One heater I use in the dining area where my desk is. This is where I hang out when I get home from work. This one runs for about 5-6 hours an evening on warm. The one in the bedroom for 1-2 hours and maybe 1/2 hour in the morning in the bathroom.
My electricity bill that covered December with the central heat set on 60 unless I was home and then it was 68, was $124. My bill for January which had about the same amount of cold days and nights, using only the ceramic heaters, was $53.
I have similar results in the summer with the 2 window air conditioning units although the cost is greater due to increased use of the a/c in the bedroom. All in all smaller units for limited areas of use work best to save me money year round. It may not work for those with more people living in their home and probably not for those in colder climates but for a $25 investment you might see if one might work well for you.