Bring a kitchen timer --- a noisy, plastic cheap one. Set it for the time limit to listen to the sales person and set it so both of you can see the face. I, personal, put it ON my pocketbook (to me a symbol of MY PERSONAL PROPERTY.. DO NOT TOUCH). Click, click, click ... counting down the time.
Be polite, ask no questions, response in very few words to their questions, look long at the pretty pictures and say, Thank you. DING, stand up, gather your stuff and ask for the paperwork to take to gifting... saying only "thank you; not interested". Ask a second time slightly louder and for the third time, ask for the Floor Manager loudly while walking towards, the "boss pit" ... where all the sales staff goes for a 'better price'. Trust me... every "mark" THINKING of buying, watches their sales person go to the "boss pit" .. you become a BIG DISTRACTION to the selling effort to everyone on the floor. You will get attention .. but your goal is to get OUT with your possible gift, NOT arrested. As a woman, the effect of me saying, "DO NOT TOUCH ME" means something very different than when a guy "glad hands" another male on the back. Oh, and if someone stands in your way between you and the exit ... ask "please move" or just stand there silently glaring eye to eye.
The salesman biggest tool is their words; your tools is a glare and a single word, "NO". If 'no' is not the word which applies ... your glare works by getting the salesperson to just run their mouth MORE.