Our yougest dd has a 12/20 b-day, so I know what a budget cruncher those close to the holiday season birthdays can be!
For the party we had this year for dd who turned 6, I think we had the cheapest "goody bag" ever (and I have three older kids).
I simply purchased those craft sets (Disney themed) they sell at AC Moore and places like that (I have also seen them at the Dollar Store and in the Dollar Spot at Target). They include a hard (like sturdy cardboard) surface with a scene to paint (usually 2 or 3 scenes included in each box), waterpaint, and a brush. Both of my dds enjoy these (older one is 10) and they are great to pull out for a special craft treat now and again.
Usually these are a dollar, I bought during a special promo so they were 75 cents. I taped a candy cane to each one (box was 12 for a dollar), so total cost was about 83 cents a kid.