Guess I'm bored now that college hoops season has ended, so I tracked the evolution of FBS/Div 1-A membership since 1981 using information from sports-reference.com. Here it is:

2015 130(?) +Charlotte, +12th SBC school(tbd)
2014 128 +ODU, +App.St., +Ga.Southern
2013 125 +Georgia St.
2012 124 +UMass, +Texas St., +UTSA, +So.Alabama
2011 120
2010 120
2009 120
2008 120
2007 120 +WKU
2006 119
2005 119 -FAMU
2004 120 +FAU, +FIU, +FAMU
2003 117
2002 117
2001 117 +Troy
2000 116 +USF, +UConn
1999 114 +MTSU, +Buffalo
1998 112
1997 112 +Marshall
1996 111 -Pacific, +UCF, +UAB, +Boise, +Idaho
1995 108 +UNT
1994 107 +ULM
1993 106 -CS Fullerton
1992 107 -Long Beach, +Nevada
1991 107
1990 107 +Ark.St.
1989 106 +SMU
1988 105 +La.Tech
1987 104 -SMU, -Wichita, +Akron
1986 105 -MVC(Drake, WTAMU, Ind.St., Ill.St., SIU)
1985 110
1984 110 -W&M, -Richmond
1983 112 -UNT
1982 113 -Ivy League, -SoCon, -Southland(excl. ULL), -Holy Cross, -Colgate, -ULM
1981 137 -Villanova
1980 138

1982 appears to be the year that schools and conferences had to meet the new Division 1-A requirements or move down to 1-AA.

A couple of comments. First, the current realignment period has experienced the greatest number of upgrades from FCS since the late 1990's. This is based somewhat on the need for conferences to add schools to survive. More importantly, though, it suggests that the financial benefits of FBS membership outweigh the costs for many schools. In particular, the new BCS pool of money covers the cost of additional scholarships. There will probably be other revenue streams as well, such as increased payouts for one-and-done road games vs. major schools, increased tv money, and increased donations and ticket revenue for home games. I dare say that the current group of schools moving up to FBS is one of the big winners in the current round of realignment and the new BCS system.