Business Ethics

In class I learned that the Talmud states that one is not permitted to go into a store and seek advice about what to buy and then go to a different (possibly cheaper) store to make the purchase. Granting this, what if the store person knows that you are ethically bound to make your purchase there and seeks to take advantage of that obligation?

If the salesperson is aware of your ethical obligation and he takes advantage of it I am not sure that your obligation demands that you incur a financial loss because of it. However, in all events, the best way to get around all possible Jewish Law issues is to tell the person serving you that you are only making enquiries and that you have not yet made a decision as to whether you are going to buy the item in question from there or not.