That is not a bad price at all, for a Sony LiIon.
You did good.
Sony is the best. Japan knows how to build some electronics.
Taiwan battery's are junk, I have tested a bunch of them. Hard to beat a Sony.
The most important thing about Lithium is they Don't like to be dead. A good charger is good to have. Keeping them topped off helps for better longevity.
They normally have a low shelf/self drain rate, but if they do go dead they do not recover very well.
They can also be hazardous to recharge if their voltage gets to low.