Add Units of Measure to PDPs

Hi there,

I'm looking for a way to add a unit of measure descriptor by the quantity box on a Squarespace site, preferably using tags. For example, if there is a product sold by the ton, a "per ton" tag would be used to display a "number of tons" text descriptor on the corresponding PDP. Additionally, I would also want this functionality to work for other tags such as "per cubic yard". 

Any thoughts on some Javascript that could injected to pull this off?