Does Anybody Knows When Kelly Book Value Is Changing #(monthly, Yearly

[adi]

Hi, I would like to buy a lexus sc 430 and the price is still 5K more than I want to spend(30K for a 2002 model with aprox.50,000 miles). I noticed(after several phone calls) that sellers usually are guided by kelly book value ( on cars.com). I was wondering how often the prices are changing in kelly book? Monthly, or maybe in january each year? thank you in advance for your thoughts in this matter/

[SKperformance]

It changes bi weekly as it is produced every other week by having people record the sales prices for cars at wholesale auctions and comparing it to resale site for price comparisons to list.