Remote battery packs cost about 1-2 bucks if you make your own 10-20 units at a time. It's not a hard thing to make.

I'm in progress of converting *almost* all of my games to NVRAM.

The only downside I've found is that RTC (real time clock) doesn't work with NVRAM. It's not an issue on most games. A few games have a special 'midnight madness' mode that depends on RTC; and TZ matches the clock on the playfield to the RTC

So, my TZ gets a remote holder with 3 alkalines.

Cost is a concern on NVRAM, I bought enough to outfit all my games and got the cost down to around $15 a game. But, the supplies of DIP NVRAM are pretty much nil at this point, so you have to use an adapter.

Even at $30 a game through somewhere like Big Daddy Enterprises, I still think it's a viable option if you are capable of installing it. One board repair that involves cleaning up battery damage will cost more than that, even if you do it yourself!

Lithium batteries don't impress me. I'd rather do a remote battery holder with inexpensive alkalines first. The amount of work to neutralize lithium and clean it up doesn't sound like it's as friendly as cleaning up Alkaline - which is no fun at all!

FWIW, games going through my workshop will be leaving with NVRAM going forward, unless the game has a RTC, in which case it will get a remote holder with regular alkalines.

Don't forget, there are lots of real looking, counterfeit batteries floating around... if a deal is too good to be true...