I have sold rebuilt batteries, they don't work that good, lots of complaints, its like a lottery type situation,3 out of 10 would go on for 2-3 years, others would go off 3 weeks to 3 months. They are refurbished, due to that only a maximum of 80% is restored, this means you would get 80% of new battery. that is the maximum restoration, sometimes they are only restored up to 50-60%.
I would suggest you to buy original as you would be satisfied about the authenticity.