Spend only what your family can comfortably afford!!! DO NOT go 'all out' to try to impress others...what you can safely spend, without going into debt, is what you should spend....there are many ways to have a wonderful party and not go into debt...this goes for all the items you mention; your dress, shoes, etc...
I also think it'd be a nice gesture if you could do some of the work yourself, or at least help out with the preparations...try to make it as easy as you can on your parents; don't saddle them with unnecessary debt for just one party!!
When they realize that you are not a 'spendthrift' with their money, they will certainly appreciate it!!!!
And you will have a wonderful Sweet Sixteen party, knowing that it was an event that didn't make your parents go broke!!!
Have a wonderful time....take lots of pictures!!!! You will always cherish them!!