I'm probably late to the NVRAM game, but thought I share my experience. I bought 5 chips of FM1608-120-PG from EBay for about $30. They showed up today. I (gently) took out the batteries and popped out U212 from one of my whitestar pins, put in an FM1608, powered the game back up, changed some settings (e.g., free play), rebooted the game, and everything worked like a champ. Couldn't have been easier!
Link to Ebay: ebay.com link
EDIT: There are some links in this thread for NVRAM (Aliexpress) that costs around $2.50. People have received these and have reported that they work.
UPDATE: July 27 2017
Here is a link for someone selling these for $1.50: https://www.aliexpress.com/item/FM1608-120-PG-FM1608-120-P-DIP/32596337719.html