Why not continue to use the giveaways to draw in new members, but allow contributing members to enter giveaway contests more than once. One additional entry per toe, as it were. You still have new members joining and entering for free, but there's also an incentive to donate and increase your chances of winning a giveaway contest.
That's part of my multiple personality disorder ...It looks like you have two accounts: Hope'sMom and HopesMom. I added it to the other account. Sorry about that, and thanks again!