We had bday parties every other year & my 16th bday party was one of them. I don't remember right now what we did, but for my 12th bday my mom worked at the Y & got insane discounts on stuff. She bought a bunch of stuff to make sub sandwiches, got a pool party package (not the pool, we just got to swim in the pool for a couple of hours) & rented a room there for the food & gifts portion. My 18th bday my parents got a party package from our minor league ball team (May baby) which got us 8 tickets, dogs & a soda for everyone, a visit from the mascot, an autographed pennant & card from some of the players & my name on the scoreboard. Is she into basketball or hockey? We had a blast!
If that's not in your budget, how about buying a bunch of fun colors of nail polish, or have each guest bring some (label them & save everyone the headache of sorting later), borrow foot spa tubs from friends or get some rubbermaid tubs that'll hold teenage girl feet (great for storage later), foot scrubs & lotions (Bath & Body Works is having their clearance sale right now & have some great deals!)... for gift bags check the dollar store-I got a mini pedi set from Santa in my stocking. For $1 I got nail clippers (they shouldn't share unless you wipe them down w/alcohol between girls), toe separators, cuticle pusher stick, a foot file (not sure what it's really called) & an emery board. Have her invite a few girls over & if it's a small number, do the pedis yourself. If there are more girls, ask girlfriends if they want to come over to help you & hang out in your own area afterward, or have them do each other's feet. The mani/pedi stickers are great fun & relatively cheap too, for the finishing touch.
Happy birthday to your daughter!