Find alternative price

Hi all.

I have this measure to calculate the total sales based on a price list.

The thing is that my date range starts before "ItemPrice[StartDate]" on some items.

When this occures want the oldest price on the item to be used.

For example if StartDate is 01.02.2023 and EndDate is 20.02.2023, on the date 15.01.2023 i want the value on 01.02.23-20.02.23 to be used, because there is no older dates in StartDate for this item.

NewSales = 
SUMX (
    DateTable,
    SUMX (
        FILTER (
            ItemPrice,
            ItemPrice[StartDate] <= DateTable[Date]
                && ItemPrice[NewEndDate] >= DateTable[Date]
        ),
        [SalesQuantity] * 'ItemPrice'[Price]
    )
)