If you have a ham radio license I’ve negotiated a discount, it’s around 25%.
To obtain a discount code go to https://milbatteries.com/
In the comments request the ham radio discount code. Provide a copy of your license (I provided the link to my license from the ULS and that was OK).
You will get a code via email.
Go to the Optima battery site https://www.optimabatteries.com/
Enter the discount code at checkout. The code is good on their batteries and chargers.