For each cell in column check match

lets say I have part numbers in col A a with prices in col D of workbook 1. I have to match col A with 30 other workbooks part numbers all of which are in col B of respective workbooks. I need to run through each of the workbooks and if there exists a part number that isnt in first list i need to add it to first list. also.. If the price for each part number is greater than first list I need to swap prices.