Gas and Oil Home Heating Furnaces - Additional Room Heating

Our house is heated by an older forced air gas furnace.
There is only one duct, (that we can find, since the previous owner installed accoustic ceiling tiles that we are fearful to dislodge at this point), into the rec room & it is very chilly.

We have been trying to decide what is the best source of
alternate heating.
In Ontario, Canada, the energy, and subsequent costs for a
baseboard or ceramic heater are outrageous.
We've read about the oil heated rads that are stand alone, and
do not run continually, but only once the temperature drops.
We're not really crazy about having a combustible source, like
this, or a propane heater, but are at a loss.
If anyone can advise the pro's and con's of this oil rad, or something that is preferable, we'd appreciate it.
By the way, we plan to replace the furnace by next winter.

Thanks,

Forum Moderator Note:
Subject line edited to consolidate wording.

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Tom_B