Yup, they are expensive. I have one of those batteries in my NSX. There was a group buy on 6.5 lb batteries over a year ago on the M5Board.com forum. I used this battery in a 300ZX, then had the battery in storage for nearly a year after I sold the Z. I have had it in the NSX for about a month, no problems so far even after not driving the car for a week. I have a battery tender to keep it charged if I know I won't be driving the car for over a week.