I love goodie bags! I love making them...giving them etc I still do them for my kids for their parties and they're 10 and 13. No complaints yet! LOL!
You could do all kinds of things...new baseballs, individual packs of cookies or chips (some sort of snack item), decks of playing cards, sm flashlights, gag items like whoopie cushions, hand buzzers etc (those are always a hit in my goodie bags LOL), coupons for an ice cream at some place (I do a local place in our town)...
I can't think of anything else right off...it's past my bedtime. LOL I do buy stuff for goodie bags, all year round, so when I see something on sale - I just pick up a bunch of them with the goodie bags in mind, so it works out well for me. Is it really costly for me? Not really...I don't buy 'junk' (at least what I consider junk, it's not stuff from the dollar store or anything like that) and I've been complimented on my goodie bags by many parents over the years - someone always calls wanting to know where I found one thing or another. Last time it was the sticky eyeballs...big hit. LOL