This isn't what I normally do for clients ... at all.

But I write Excel formulas and custom-code databases every day and have a solid background in statistics.

Sounds like what you're asking could be done in an hour using Excel ... and in such a way that you'd be able to enter future data in the spreadsheet on your own and have it analyzed automatically.

Maybe software exists. Maybe you can hire someone on Fiverr. But if neither of those options works for you and you're willing to overpay someone overqualified for the task, I suppose I could set it up. Might be a nice break from real work!

Go for a specialist who has work in data analytics spectrum, someone who has good business and statistics knowledge. There a number of freelancers and reputed companies, www.marketquotient,com can surely help.

Excel is still a solution for a big deal of your needs .

But for visualization you need to check "Tableau".. It is a really different experience that will take you in a different dimension.

For a deeper statistical analysis , you may go to mini tab , which has an edge on excel when come to statistics.. But still visually , tableau is waaaay better .

I'm a data scientist and look into questions like this frequently. Until recently, I ran the data science organization at a payment processor, where we answered questions like this for merchants on a daily basis, and also built products at scale to help inform merchants' decision making.

The question here really is: can you predict these sales numbers well enough to inform specific buying and manufacturing decisions? Sales numbers are difficult to predict precisely for many reasons (week to week fluctuations can be pretty high, seasonality can be a big factor depending on what you're selling, it's very helpful but often difficult to separate sales from existing and new customers, etc.), but as long as you can predict them well enough and far enough in advance to make better decisions you can create a positive financial impact. The point is that this isn't so much a question about predicting the sales as well as you can, but a question about optimizing your decision making process.

Therefore, I'd encourage you to engage the help of someone who has experience in solving operational business problems using data. One of the first things a good data person should do is help you quantify the size of the problem - how much money you can save by doing this analysis. This will help you determine how much time and money to put into it to make sure that the project has a positive return on investment.

Projections are not only based on data but also on operations, products, people and process. There are couple tactics you can use without mapping a large data.

Other things you should look at are the people who execute behind your products because mostly they are the one causing sales problem, not the product or its data projection.
By implementing couple tactics you can figure out easily the product that sells most, your A players people, and implement a marketing strategy that sells.

Give me a buzz. We can set up together the process for you.