Item Pricing (from SuiteScript)

Hi,

We invoice customers "Other Charge for Sale" items on a periodic billing cycle (either monthly, quarterly, or yearly).  We are about to implement a price rise in some months' time, so we created "New Item Pricing" records showing a "Valid From" and "Valid To" range for the various prices.

The periodic billing SuiteScript that runs each month which generates the invoices does not pass the item price to the invoice - it simply passes the item and the price 'appears' upon saving the invoice.

How can I access the Item Pricing records from within an "Other Charge for Sale" item from a SuiteScript such that I can correctly allocate the relevant Item price for the relevant future period - e.g., the Item price for next month is different to the Item price for the following month, yet it's all on the one invoice (as separate line items).