I am a participant of a retreat that meets every two years. I watch the clearance bins at walmart or any other place that has sewing or specials on something. Last time I found 5 120 in measuring tapes on clearance at Walmart for $2.50. I found sewing nippers for $3.00. I found note pads for $1.00 at Target. I watch the catalog for "home-sew" for what they may have on special. I try to get everyone's name, address, phone number, and email address and go to Office Depot or similar and buy fancy business card stock and make everyone some business cards they can exchange. I usually wind up with 10 to 15 items for the bags. I use my computer and make about 20 cards for each quilter. I watch for different craft websites and look for the good sale items. I do the same for the door prizes. Each bag is usally different because I can rarely get 20 of an item. After they look at their bags, I don't mind if they swap among themselves. Last year I found plastic cases for rotary cutters for 75 cents. I bought all they had, about 25. They ones not given out are on hold until we have new people coming and then I pull out the stash. Start early and keep looking.
Last retreat we made a cell phone purse. I went to Hobby Lobby and bought lanyards for 1.00. I wish I had bought more. I am about half way finished for next year's retreat.