Wait, are you going to model each customer, and calculate stats based on how they liked each product in the market on the fly? Because that sounds like it would be a lot of number crunching and data storage that really isn't needed.
Look at it from a 'market trend/desire' stand point, and grow or shrink them over time. So you have an overall desire for Product Type X, which then has market desires for various features. From that you compare the various products of Type X on the market, and calculate its market share. You can achieve a market simulation using just dozens of values, rather than millions.