I was having financial difficulties this semester because of a few unforseen car problems (gotta love those). I approached my chapter and was given a few options and the only one that worked for me was to promise to pay what I could through the end of the semester. Lucky for me I'm moving so I'm being granted alumni status because I'll be transferring and next semester would be my last in Chi Omega anyway!
I would simply approach YOUR executive board and work out a payment plan for you. If it's REALLY important that you be considered alum then you'll find a way. And likewise, if they're true sisters, they'll make a way too!
Good Luck and let us know how it goes!
Hootie