Replace data in Excel 2007

I am at a loss on HOW to take the data I have in one sheet and update it from another (data feed). All cells have a unique value although the information I want to replace uses the same formula. Exactly what am I doing? I have all of the product I sell including quantities, pricing, etc in on excel sheet. All product has a unique id. I need to update what has become in or out of stock, but more important is the fluctuation of MY cost on items … so I need to change my selling price frequently for thousands of items. Can I somehow MATCH on the ID … AND at the same time CHANGE the value of the sale price? Any directives would be greatly appreciated. Thanks in advance … Lisa