Limonene. Can be had without additives or markups. Get what’s called “technical grade”; it’s what the direct product is from extraction without a lot of purification. Higher purity grades are expensive and not needed unless you’re using in as reagent in a chem lab.
It can be skin irritant, so wear gloves. It’s NFPA 704 health rating is 2 (same as DCM), so don’t breathe the fumes.