We have an only, so we don't worry so much about sticking hard and fast to a budget. Having said that, I am pretty frugal and think that a birthday party can be celebrated with cake and ice cream in the back yard just as easily as it can be at the local bounce house! We have done a variety of things for DD over the years, depending on the circumstances. I usually tried to hold it to about $100 for a party, whether at home or out. Birthday at our house always means cake and ice cream, and dinner out (at a family restaurant like Olive Garden) or your choice of what to have for supper at home.
DD's birthday is the third week of September, so often I kept much of her back-to-school clothes and gave them as birthday presents. She seemed to do much of her growing over the summer so she needed new sizes by her birthday, anyhow. She also would get a variety of smaller, fun things. Now that she is older, the presents cost more, and as she buys her own clothes as she needs them, these are not part of the gifts either. We usually try to get her something she's been wanting but is out of her price range. Last year (19th birthday) we got her a net10 slider phone so she could type-text and hooked it to our credit card so we pay the monthly bill (before that she had a trac fone and knew that the 400 minutes we paid for had to last the entire 3 months. She was good about this- but was ecstatic that we upgraded her to this phone). This year, we went all out and bought her a MacBook Pro. She used graduation money in 2011 and bought a Lenovo, which is old, heavy, awkward, and confused by now, so after losing school work or not being able to access course info, etc., she used her savings in April 2013 to buy a Dell. The Dell's hard drive crashed in late August! Yes, still under warranty, but really? Three weeks' repair time? I inherited a MacBook Pro at work and knew immediately that I wanted one for DD for her 20th birthday. We gave it to her a bit early, right after her Dell went in for repair. She is ecstatic!!!
Now I am gearing up for her 21st. She has said for years that she wants to celebrate it with us at Disney, at the Food & Wine fest, so she knows what we are planning. What she doesn't know is that I am going to try to get a safari view room at AKL as her "surprise" present. The trip itself is for the whole family (ok, all 3 of us) to celebrate her 21st, but we always stay offsite or at a value. If I can swing a safari view room, she'll DIE. It's been her dream (and mine) since the very first time we set foot in AKL to go to Boma!