Essential oils and vegetable oils (like sunflower oil) don't often make great solvents for extracting.
10x orange oil works, but I wouldn't use it for consumption; I just used it in a final pull for some "Galactic Temple Incense" as a joke gift to a fellow Nexian. The high limonene content makes for an adequate substitute if you don't plan on consuming your product... But the moderate amount of other (sometimes unknown) chemicals makes for a poor solvent for smokable or edible DMT extraction....
Lemongrass, unlike orange oil, has nearly no limonene in it at all. If it's for use in lamps, it's probably cut with another oil as well, as pure lemongrass oil is volatile and prone to fast vaporization under heat, not even burning. Furthermore, essential oils shouldn't be used for consumption at all; many contain high amounts of toxins found only in small traces in the source material (A great example being Thyme or Basil oil, a large bottle of which can contain a lethal dose of thujone).
Pure D-Limonene can be easily obtained in-person or online and makes a great solvent. You can find this online through cosmetics suppliers, bio-diesel and soapmaking suppliers, herb shops, chemistry supply houses, gardening stores and many other places. I recommend cosmetics suppliers or chemical supply places, which can give very clear information on exactly what is in your solvent.
I remember a vegetable-oil based tek posted on the Nexus at some point (possibly years ago), but I don't recall whether or not it was really viable. It seems to me as if it would be a challenge to get the actives back out of the solvent, since oils can't be varied in ph like aqueous solutions.