The following blog giveaways had less than fifty comments each (at least when I found them). Pretty good odds! (Organized by last day to enter).
$100 Home Safety Kit (17 coments)
Clayful Creations (29 comments)
Justin Roberts Jungle Gym Kids CD (30 comments)
Choice of Children's CDs (20 comments)
The Last Christian by David Gregory (44 comments)
Prayer Cards (19 comments)
Fever Dream Audio Book by Lincoln Child (60 comments - 3 Prizes)*
*Yes, this one had over 50 comments, but because there's multiple prizes, it brings the per prize chance of winning down to less.