Got 2 sets for 49.98 with each package bringing 2 batteries and a charger.
1 set goes for $24.99 so check it out!
Super slim battery better fiited than the 1800mAh ones I posted before from buy.com
Plus if your planning to upgrade from Samsung Galaxy to the S2 you can carry over the battery.
Choose the free devilery and you still get it shipped just faster than the date they expect to arrive.