If you're shopping for a big day or special occasion, your budget is usually higher than normal. You shop around with purpose, with a pretty specific idea of what you want. It could be a suit for a friend's wedding or maybe just a good pair of jeans you need for your birthday.
You will be making a mistake though if you let the salesperson or "store assistant" in on what the occasion is. If you're shopping for a suit and you mention it's for your wedding or engagement party, do you think they're going to point you to the suit on sale or to their five most expensive? That question, "What's the occasion?" is a trap. Always downplay the occasion. You usually already know what you need to get. You really just want the salesperson to point you to the blue suits or a pair of stonewashed jeans. You don't need them to advise you on which brand or style you should settle on.
Notice they won't ask you for your price range or budget limit. What they will do is try to overwhelm you with the sense of occasion. "It's your wedding...it only happens once...it's the most important day of your life," they will quip as they tug at your emotional side in an attempt to muzzle your rationale. I can feel your purse strings loosening from over here.