2 criterias to organize data by VLookup

Hi,

I have a sheet with the following fields:

Date | Company | Price | Item

So I will input data on it, like this:

03/28/2013 - Acme - 1.000 - Jetta

and so on. Different company names (but its fixed on 6 or 7). Itens can be a lot.

So I want to make a graph that will show me the evolution of the prices for each company.

So I need to organize all these registers with 2 conditions: get price that have same company, on this month for this item. So I can compare same item with same item, same month with same month.

I don't know how to do that. The formula I know is for 1 criteria. This is 2 criterias.