Modeling products pricing structure

I need to model a rather complex pricing structure for some of our products.

Today we lookup the prices manually. Here's a picture with explanations of the "matrix" that we use today: Sample model (sorry for the link - but I'm not allowed to post images because I've just opened my account.)

Now I need to transfer this model to a RDBMS system (SQL Server 2008 R2). The entry point when looking up a price is开发者_JAVA百科 the Category, then the yearly interval and finally the interval depending on how many products we're selling on this order. The result of the query should be two prices.

Do you have any suggestions on how to model this? I was thinking of modeling it as a matrix with a RowNumber, CellNumber and a CellValue. But then I need another table for describing what is contained in each cell (by referencing the row and cell numbers). If doing that, I could just include the prices in that description table. But that doesn't seem like the best solution.

Do you have any hints/solutions on how to model this problem the best way?

I think I would make something like this:

Categories are separated into its own table. Each row in the price table are uniquely identified by the category and starting point of the sold and shipped range. I don't think you would need to specify ending point in the table (since the end point of a range should be the starting point of the next range minus one).

Edit: With this model, you will need to add a row in the Prices table for each combination of category, units sold-interval and units shipped-interval, but right now I can't think of an easier way.