There are a huge number of ways to do this: but assuming that the two files are not necessarily in the same order, I would create a class which contained the Price and Description (call it "Item" maybe) then create a Dictionary of Items:
private Dictionary<int, Item> items = new Dictionary<int, Item>();
I would then read each file in turn, breaking it into itemcode and either Price or Description and do this with each row:
items.Add(itemcode, new Item());
uncommenting the appropriate line.
At the end, you have a Dictionary which contains each Item, hopefully complete with each Price and Description.
It's a poor way to store your data though!