Why do you need to run updates every minute? Are people going to be updating it that often, if they are making orders for a day or week?
I would start with deciding on the equations that will be used in your model.
Then, that will help decide what you need in the database, to give the parameters to the model.
Then, once you have the database, you need to get information from the user, so decide what you need from the user.
For example you should have some random event that will make certain items go up or down in demand, or have resources become more common.
So, you may want to have information in the database that lists what each product is composed of.
If the model will have external information, or, if it is based on what others make, so, for example, last week shoes were not produced, so those that made shoes made a profit. This week everyone is making shoes, so there is too many, so the price went down.
This is why I think starting with your model, and testing your assumptions is the first step.
Any language, system, database will work well, just do what you feel comfy with. When you design the UI, do you want it to look fine on iphones and the Blackberry Razor? Then that will have a big impact on how you design the UI.