Our school uses Jostens, and I've been answering that very question for seniors for years:
When you buy your cap/gown/tassel set, you get all three pieces that're necessary for graduation. That is the tassel that you'll wear for graduation -- it's the one that'll match everyone else's. However, TODAY you're just ORDERING the cap and gown set. It won't arrive 'til spring. This set costs $9.99 and the shipping fee brings it up to around $14.
If you want a cool tassel TODAY to carry around school and show off that you're a senior, if you want a cool tassel TODAY to hang from the rear view mirror in your car, they sell those as well. I think they cost $7 or 8 and are available in several different varieties (mascot, bling number, whatever). These tassels are a little larger than the ones that come with the set -- they're meant for showing off; not wearing at graduation.
Yes, compared to the whole set, the single tassel is a poor bargain, but here's the behind the scenes info: The county "takes bids" to see who'll sell the necessary graduation items to our students for the lowest price. As long as the company sells the cap/gown/tassel set for a rock-bottom price, they're allowed to sell other items (scrapbooks, mugs, sweatpants) for whatever price they like -- the county is only concerned that everyone can afford the graduation clothing.
Two other behind-the-scenes scraps:
If students don't order with the group in the fall, the company doesn't have to give them the $9.99 price. Students who order later on their own will pay more. So in October/November, the group order people pay $9.99 . . . but the person who orders in December pays maybe $40 . . . the person who gets around to ordering in February probably pays $60 . . . the person who doesn't order 'til May or June may well pay over $100 AND will pay for Fed-Ex to deliver it to his house. This is no secret: Jostens tells the kids. The teachers tell the kids. It goes home in newsletters. Still, a good 40-50% of the seniors don't order at the $9.99 price, and then they complain that they can't afford the items. And parents are no better, saying, "With his grades, I don't know if he'll graduate this year. I'm not ordering 'til I see that he's in the clear." Why wouldn't you pay $9.99 now to avoid paying $100 later? Jostens accepts returns on unopened cap/gown/tassel units, or they exchange them for a next-year's set. I have no sympathy for people who've been told and have ignored the information.
The other thing to realize: When you get the Jostens paperwork, they promote three color-coded packages at the top of the page -- the cheapest is around $150. These include the cap/gown/tassel set as well as a large number of announcements and other items that you probably don't want (2012sweatpants, anyone?). The paperwork is designed to suggest that you must choose one of these big packages. Not so. Students can order JUST the cap/gown/tassel set and a couple announcements. Line-by-line orders are a choice, but they're at the bottom of the page and are written in small, B&W ink, so they don't stand out like those three big packages.
My daughter's a senior this year. At the end of the summer I helped her open her first checking account, and I gave her the money she'd need for all her school stuff: Class fees, parking pass, money for her lunch account, etc. If she'd needed college application fee money, I would've given her that. For her graduation items, I gave her $100 and told her she could buy what she wanted and keep the rest -- she bought the cap/gown/tassel set and a mug with everyone's name on it. We agreed that we're going to do homemade invitations. Since it was HER money, she found her desires greatly reduced.