Responding to the last two replies, re what I actually charge besides the sitting fees. Last year, after reading everything I could find on the topic of dance studio photography, I realized that I got myself involved in a part of 'the business' that apparently is the least lucrative. Part of the problem is the cost of dance lessons, especially for those parents that have kids in 'company' We're talking an average of $10k in costs a year. And since we usually take the photos near the end of the season, the parents are worn out, both emotionally and probably financially. That's my opinion.
Also take into consideration that this is not like taking photos of a Little League baseball team or Pee Wee Football. Those kids have one uniform. That's easy. With dancers, some kids only take one class, a few take two, and then you have the company dancers where it's not the 'class' that is important....i.e. ballet, jazz, hip hop, etc. It's how many dances they are involved in when at competitions. My daughter had one solo, one duet and seven group dances.
My dilemma was, in part, how to charge sitting fees that are fair to all involved...including me

Would I charge $90.00 in sitting fees for a dancer like my daughter? There's no way the parents would do that....
Last year was my first year doing a dance studio and after studying order forms from previous photographers and some I found online, I was even more confused. Most of the forms I found were confusing at best. Part of that is the nature of the beast as I mentioned above. Anyway, last year I offered the typical A, B and C packages that ranged from $25.00 to $45.00
The $25.00 package included: two 5x7s, 8 wallets and a 4x6. Several people ordered more than one package and it was SUPPOSED to be for one pose only. Somehow I let them get away with ordering individual photos....from me (as opposed to ordering online). Oh...and I listed as $27.95 if they waited and ordered online. So by paying in advance, they saved a couple bucks.
I also offered 'online credits' as follows...
$35.00 in credit for $27.50
$50.00 in credit for $40.00
And so on...five levels.
The results were evenly divided between the packages and credits. And there was 'supposed to be' a $10.00 sitting fee. I'd say maybe 70% of the parents actually paid that even though it wasn't optional. That's because that first year, which was over two nights, it was a little chaotic because I was promised help to take orders and didn't get it until after I was shooting for two hours.
This year I'm doing it differently. No packages. Optional sitting fee of $10.00 and the sitting fee goes up if your dancer has pics taken in more than one costume. I only offering a discounted online credit. This way, once I upload the photos to SmugMug, and then send the credit coupons to those that paid, I'm essential done, except for extra orders.
The credits range from $25.00 to $100.00 and you get 10% off by paying in advance (which is a smaller discount than last year)
Last year actually turned out fairly well. I can't say that I'm expecting to gross more $$ this year but I DO know it'll be way less 'work' after the photo shoot.
As a 'dance dad' we also go to several competitions each year. Most of them have photographers that sell the photo right there (and you can order online after the event).
I mention this because the prices were all over the place this year. Most of the time they are charging around 20 bucks for a 4x6. Over the last two years, I bought one. Not the best quality either. At our first event this year, the guy was charging $15.00 for a CD of every photo they took of any dance. We bought two of those and two videos...same price. Great deal. (for the parents) And what I noticed was that he was busy fullfilling orders all day while the group that was charging 20 bucks for a 4x6 was never busy.
Sorry for the long post....and good luck with your shoot, dewsgirl. My shoot is next Tuesday. I hope my paper backdrops arrive on time