If it ever makes into reality (I doubt it will), you will be given a simple choice: pay whatever some algorithm believes you are prepared to cough up even if it's more than everybody else, has overestimated your income, net worth, etc, etc; or go to a high street store where you pay the price on the sticker, no questions asked. This scheme could be just the saviour that the high street has been waiting for.
And to those who say it's only a form of bargaining and the workings of supply/demand market forces, imagine your employer giving you a pay cut because they heard you just inherited some money from a recently deceased relative (after all, you don't need as much money now, right?) There's already a place where supply/demand forces work in the way they were intended - it's called eBay.