There is always a non-OEM option but whether it is worth the money is debatable. I have just ordered a replacement NiMH battery pack for my VX-170 which I bought back in Mar 2008. I saw someone selling a LiPo pack and charger that had a better capacity for about £35. The pack had a smart battery controller in it. Or it claimed to have. I wasn’t sure how it would work with external 12V supplies and the charger came with a EU plug not UK. So there were minor issues that would need solving.
However, it was a direct from the Middle Kingdom on eBay so it would attract “sales tax and duties” when it got to the UK. Based on my experience of buying from Chinese eBay vendors and the chance you may get a load of total junk with no warranty compared with the fact that the original Yaesu battery only lasted 12 years I decided I’d buy another genuine item at £28 inc. P&P with lower capacity and more weight but with some possibility of quality control! 
You pays your money and takes your chance… Yaesu OEM with warranty please.