Lookup with criteria / Index match (?) / Using dates

Hello guys
I´m not sure which functions to combine to the desired result. I've uploaded the sheet, it is in portuguese but that won't matter much I hope, I'll explain the best I can.

What I need to do is:

On the third tab (Cobrança), column H (Valor unitario de compra), I need to do a special lookup from the second tab (Valores ENTRADA + SAIDA), bringing me the value from column O (Saldo V. Unitario).

The conditions are:

1)Matching the product from column D from the third tab with the second tab (column E)
2)Must search only from rows with the string "compra" on column B from the second tab
3)As the value searched is dynamic, the date from second tab must be the LAST, EQUAL OR PRIOR, the one from the third column.

Example:

The first data on the third tab is hashi sticks sold on 16/09. The value searched on second tab is O160, because its the unit price of the product on its last purchase, 21/08, prior to the sale's date (row 160).


This seems a complex task to me so Im not sure how to begin solving it.