These are just a couple of the parties available, the Illuminations dessert party in Epcot, a Fantasmic dessert party in MGM or the Mad Hatter Tea party, which is usually in the quiet pool area of the Boardwalk.
Illuminations and Fantasmic will run you $12.50 pp for viewing fee, tho if anyone has a ticket that was good for that day in the respective park, you don't have to pay the fee, they just show tickets. I believe they both have a minimium person requirement, but that can be covered for smaller parties by ordering the more expensive menus. I think the menus start around $17.50 pp. I believe there is also a pp set up fee if you would like tables and chairs.
The Mad Hatter Tea Party can be very expensive (especially if you get the props, floral and characters), but can also be done more economically, as well. The budget I saw was approx. $20,000, but they went all out on it.
Consider joining the Disneymooners group and the Disneymooners Chat group on Yahoo groups, there is tons of information in the archives and you can always ask questions. I do know one of the women on the list is planning a Mad Hatter Tea Party.
HTH!