Genuine battery for Macbook Pro 8,2 could cost just $60, if you find a good place.
This particular place was confirmed selling genuine batteries by users, just read the reviews
http://www.aliexpress.com/item/Spec...A1286-2009-Version-MB985-MB986/729123927.html
Of course, I am not advertising. There are plenty of other good sellers at Aliexpress with a similar price
For some reason, this seller ships to USA with EMS only - not free; but shipping to European countries is free.
So, if you live in USA, you may want to find a similar seller, which has a free shipping to USA
Also, do not forget to get the necessary screwdrivers:
* Phillips #00 Screwdriver
* Tri-wing Y1 Screwdriver
* T6 Torx Screwdriver (optional)