$9.99 when I bought it...
Seller advertises 3000mah.
Battery itself says it is 3500mah.
I have found it to last about 2-5 hours than the OEM battery. It's more than 3000mah for sure. Even at 29.99 now I would be happy with paying that for the results I got having two batteries.
Base info for next comment:
Take phone of charger at 6am, 5 days a week.
OEM battery would get me through a day, all night in quiet mode and till about 1pm the next day.
One RealWay battery gets me through 2 full work days and dies while I sleep heading into the third day.
I use Greenify and had that setup for about 5 weeks since i got the phone. I changed nothing but the battery I was using.