What's the r/Frugal opinion on space heaters?

I'm a mid-20s something living in a one bedroom apartment with a cat. I just moved here in the spring and quickly learned with the summer that the insulation in this place is horrible. A/C bill topped out at a ridiculous $130 one month (Texas heat). For comparison sake a fall month with no a/c use resulted in a $35 bill.

I wonder if it's a better investment to get either a space heater (heated coils or oil) to drag with me between my couch and bedroom rather than trying to keep the electric central heat at a reasonable level.

Does anyone have any experience with the cost difference? Also any reviews of the fan-electric coil type compared to the oil-based radiators? Thanks in advance.