R31 and R32 battery price inquiry

[r2d2]

I am looking for batteries for an R31 and also for an R32 but I have no clue what's the price in the market. I tried eBay but I have no basis if the prices there are too high or a bargain. I am not even sure if they are reliable. The last one I bought there for a friend (made in China OEM, $41 including shipping) seem to have a hard time charging. It does charge but it takes a long time to get from 30% to FULL.

That is why I am throwing this question here. Because for sure I will be getting some honest (not to mention reliable) replies.

Thanks.