If the unit follows the number, then according to the accepted answer of the Including units of a measure in a range , you can skip the unit for the first value, such as "1–5 ℥".
However, that question, and the section of the source cited in the accepted answer, doesn't describe what should happen if the unit prefixes the number. Should it be
Jeans cost $10-100
Jeans cost 10-$100
or is only
Jeans cost $10-$100.