Accepting the offer from the sales rep could raise ethical concerns, as it may appear that you are accepting a bribe in exchange for favoritism in the selection process. If you choose to turn down the offer, you should be polite but firm. You could tell the sales rep that you appreciate the offer, but you feel it would be inappropriate to accept such a gift in light of your current purchasing process. You should also make it clear that accepting the offer would not obligate you to share any information or insights about the competition or the selection process. Additionally, you should not feel compelled to spend additional time interacting with the sales rep in order to gain insights into the firm's products and services.