Of the people listed two were from TN so I went with flights out of TN for a quick price search. Keep in mind all of the listed flights have different travel windows. most of which are spring. A summer trip would be a bit more expensive but not way more expensive. A winter or fall trip would be similar pricing as to what you see here.
http://www.cheapflights.com/flights-.../memphis-intl/
Keep in mind if it does not say taxes included then there is still about 200 - 300 in taxes and other charges that will be tacked on. From TN if traveling in a group I think i could find an airline to fly everyone for about 800 + or -.
Also don't feel like it is a huge rush to get on the list. The group can grow to large numbers but lets keep the list to people that are willing to commit and not back out of the trip.