Our rink (not the Club) stages the Nutcracker every year and they do a good job of keeping the expense low so that the event makes money and keeps the skaters coming back. It even brings in new skaters who take lessons and come skate, so it's all good. To that end, they have a closet of donated/created costumes that are reused every year. The Mice and Soldiers wear their own clothes - grey or black sweats for the Mice, blue pants and a white shirt for the Soldiers. The rink provides ears, tails, hats, suspenders and swords, which are reused every year. They use makeup to make whiskers, noses and rosy cheeks.
For the party scene, female skaters wear tea-length (not floor length) party dresses that look old-fashioned. Boys wear ties and vest or jackets. No one wears skating costumes since they would look odd.
For the group numbers, the girls wear black leotards, the boys black pants&shirt. They're accessorized by the rink. For example, Arabian dancers have arm and headbands and skirt-sashes to look exotic.
The Snowflakes and Flowers provide their own dance dresses and each one is unique. ;-) Ditto for the Pas De Deux skaters (which is sometimes a trio!)
I second the suggestion of using skirts over a leotard rather than a full dress - costume changes are so much easier and the skaters don't have to remove their skates.
To spread out the skirts without hoops, you can add a little lift at the waist with gathered crinoline, but it's scratchy, so "bag" it with some scrap material. It's very light and stiff, so it holds out the skirts.
Check your local thrift shops. While you might not find the fashion you're seeking, you can often find the fabric that can be repurposed. (The crinoline is used on prom and bridesmaid dresses - they can be taken apart and the fabric reused creatively.)