I have 220v electric baseboard heating in my 800 sq ft home. My power bill in winter is extremely high. I'm considering buying a 1500w infra-red portable heater to use instead. Is it going to cost me more to operate the portable heater?

Not really... they are all electric. But you could if you kept doors closed... heat one room mor ethan the rest of the house and realize some small savings there.

Do you have the possibility of Natural gas (best) or Propane? Meaning you owned the house and could make the investment, not an option if you are renting.

Kerosene prices are stupid high so I don't know if that would save anything at all.

If you are in the US electricity cost is based on the Watts times the time the appliance operates. The Electric company charges approx 12 cents per kWH...
If you run the 1500 watt heater for 24 hours, 1.5 * 24 * 0.12 = about 5 dollars.
What you did not tell us was the wattage of your overall heating system...