“Thanks for coming to our event. Here, have a bag of rubbish.” (original tweet here)
How many times have you participated to an expensive or so called high-profile event and during/after it you got a cheap congress bag full of meaningless advertising brochures, mediocre event-branded ball-pen and a non-fancy notebook?
Why ruin your event’s experience by giving away cheap stuff that most probably has a strong environmental footprint? If you want to give something out, make it memorable or worth keeping/using everyday. Isn’t it better to spend the same total amount of money (just a few cents/bucks per unit) in just one giveaway? One nice notebook (with your conference logo on it) or a small good quality booklet with information from your conference, sponsors and some original content are much more memorable. Even a [good quality] sticker is always more appreciated than mediocre swag.
Often sponsors expect/demand you to include their promotional material in the congress bag: the next time it happens, explain them that it works against them if the attendees will end up throwing it away in front of their own noses. Demand that they make a quality piece in line with the experience you are trying to create for your audience (it could even be a small brochure but with some real content that adds value to the reader, not the typical marketing yada yada).
BTW [almost] nobody needs another cheap pen… get over it and move on!