I tend to be one of those moms that goes overboard, but I am always very frugal about it.
I have three kids favorite parties we've done...
*Fear Factor age nine-boy, I bought cheap white t-shirts and did iron on transfers that said "I survived Zack's Fear Factor Birthday" on the back I put little bugs/worms and the names of the things the kids had to do/try The t-shirt was their goodie bag and cost w/t-shirts and iron on paper was about $2.75 per child
*Pokemon age 10, boy-I used recycled lemonade containers and spray painted them yellow to look like pika-chu inside the kids each got a pokemon ball (golf ball colored with permanent markers) fruit snacks, and an apple that I'd dipped in candy coating also to look like the pokemon balls, I basically only bought the apples, candy coating and fruit snacks, golf balls were recycled from a field my BIL owns near a golf course, and the containers were recycled over summer
*Letterboxing age 11 boy- I made each child a letter boxing starter kit, and a drawstring back pack from scrap fabric, the kit included a stamp, notepad, and info about letterboxing and we went on a letterboxing adventure
*Home Depot age 6, boy-I bought scrap lumber and cut peices for the kids to build tool boxes, inside they got fruit snacks and they were each given a home depot apron and safety goggles. (This was one of our kids/family's favorite parties) The wood was $.75 per child, the safety glasses were donated from my husbands company, and the aprons were donated from home depot, so I just bought fruit snacks which they won as a prize to a game.
*Chef party boy age 7, I made aprons for all the kids from left over fabric I had, I bought ice cream cone shaped bowls 3/$1 at dollar tree, and take out type boxes on clearance that were 6/$.75 at
walmart, the kids made their own trail mix, and decorated cookies that went in the take out box to go home.
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Lego party boy age 8, I made boxes from colored poster board (dollar tree 2/$1) one sheet made 8 boxes, I needed 12, inside I made keychains from 6 peg lego bricks, just drilled a hole and attatched a keychain, I bought my son a box of legos for $14.99 and picked out 12 of them to use for these. also inside was a package of lego fruit snacks, and we had a candy bar with clearance halloween candy (His bday was November) we had red licorice, actual lego candy, star bursts, and some square sour candies. I spent $8 on all of the candy (because the lego brick candy was very expensive and I splurged.. tasted HORRIBLE tho) Every one loved their goodie bags they brought home
*Care bear girl 1st bday, I made candybar wrappers as favors for guests, bought hershey bars 6/$2 printed the labels myself.
*Strawberry shortcake 2nd birthday, girl. I used pink lunch sacks and guests got to take home home made treats we made

anda bottle of strawberry soda that I replaced the label on! this was very well liked
*My little pony-girl, 3rd birthday, I collected the My little pony figures from McDonald's, my local McDonald's let me trade in other toys for left over figures they had

we also did My little pony fruit snacks, and I bought cups from oriental trading that you could put your own insert inside of, I made my own with my daughters picture I'm not sure on the actual cost of the cups, they were on clearance.
*Monkey pajama-girl, 4th birthday, the guests decorated pillow cases as their goodie bag. they were 2/$3
*Chuck-e-cheese/zebra party 5th bday-girl, I used black paper sacks, mini m&m tubes that I peeled the label off of and replaced with address labels with each child's name and filled the tube with tokens for the kids to play, also inside their goodie bags were princess tiara's for all the little girls (valentine clearance) and super bouncy balls for the boys.
sorry this post is so long, but just wanted to share ways that I have saved and still had pretty fun goodie bags!