My twins just celebrated their 4th birthday on Saturday, and I kept getting the question " How did you do all this, where did you find the coupons? For those of you that were there, I am about to spill my secrets (lol). For the rest of you, here is an idea for a very inexpensive party.
We usually try to stick to a budget of $50.00 for a birthday party, so I had a $100.00 budget for the twins.
Head on over to CityDeals, they have tons of discounted gift certificates.
We decided on Chuck E. Cheese's (for the Orem, Utah just go to All Categories and its #41 on the list)
You get a $20 Gift Certificate for $9, and you can purchase any quantity. So I bought 6 for $54, and had $120 in gift certificated to spendHead on over to Chuck E. Cheese website, and Register for their coupons. The coupons they email are Awesome!!! They are for pizza and coins. And the best part, they will let you use the coupons along with the gift certificates. CHA CHING!!
Head on over to the Chuck E. Cheese Evite. Here you can email invitations, and you can also print them FOR FREE!!!
Head on over to Ebay, and get 10 lifetime refillable cups for $14.90 shipped (that's $1.49 a cup, it would cost a lot more to buy a drink for 10 kids). Like I said these cups can be taken back every trip and you get free soda FOREVER
Take your own cake/cupcakes. I took these babies, and let me tell you they were yummy. My guest were super impressed. 
Colorburst Cupcakes
1 white cake mix
2 eggs
1 C yogurt (any smooth textured fruit flavor is fine!) or sour cream1/2 C milk
1/3 C vegetable oilCombine all ingredients until incorporated (about 30 seconds). Scrape sides of bowl and then beat on med-high speed for 2 minutes.
Divide batter according to how many colors you are using. I used 5 colors and it worked out to a little over 1 cup for each color, but each cake brand will be slightly different.
To get a layered stripe like I used, you'll want to put a spoonful of each color in the cupcake one at a time. The batter is thick, so it won't spread on it's own. A great tip is to set out a little bowl of water where you're working. Dip your finger in the water and then gently spread the batter out. The water will make it so the batter doesn't stick to your fingers.
Bake them according to the package directions, until a toothpick comes out dry
For party favors you can take some favor sacks, fill it with the Chuck E. Cheese cup and some coins. That way the kiddos have a way to transport all of the coins to the games, then when ready to leave they can use their tickets to buy stuff and use your party sack to take them home.
Make sure you show up 15 minutes early, take your own plastic table cloth ($1 @ Dollar Tree)
They let you combine the gift certificates with the coupons. I was able to get 12 pizza's, drinks for 12 adults, and over 1000 coins. Take your own cake/cupcakes!!!
6 ($20) gift certificates = $54.00
Invitations= FREELifetime Refillable Cups = $14.90
Cupcake ingredients =$5.00 (free if your a couponer)2 Plastic table clothes= $2.00
10 pk Party Favor Sacks @ Dollar Store = $1.00
TOTAL: $76.90
