Here’s another one from the Elementary Japanese book2. Takai desu ne demo harogen hietaa deyokaata desu. (I am glad I got a halogen heater, but their so expensive.)
Not sure what you are trying to ask here. you asked how to use ‘harogen hietaa’ in a sentence, then proceeded to use it in a sentence!
Also, ‘their’ is possessive. ‘They are expensive’ can be shortened to ‘they’re expensive’.
Just in case you were planning on teaching English. ;)
