Electric Beetle - prismatic cells

Hi. Im new to the inside evs forum. I did a 72 Beetle conversion back in 2015, and have put on about 30K miles in 9 years commuting to work. It has 40 200 AmpHour LFP prismatic cells wired in series. Now, after 9 years in the Phoenix heat, those cells are swelling and cracking, so its time to replace the battery pack. However, as I have started searching for a supplier, I am seeing something that has me puzzled. 9 years ago a single new 200 AmpHour LFP prismatic cell was costing $250 and up. Now I can find them new for $80 each for 280 amp hour cells. And instead of just 2000 charge cycles, the new ones are rated up to 6000 charge cycles. If those ratings are accurate, that represents a tremendous improvement in power density in the last nine years. Another indication of that is that the 280 AmpHour cells today are slightly smaller than the 200 AmpHour cells were 9 years ago. Talk about way more for way less! But life has taught me that if it seems too good to be true, it usually is. I thought I'd ask around.

Has there been that much of an improvement in power density as well as that much of a decline in cost since 2015? Does anyone have some good online suppliers that I can check out to confirm what Im seeing?

Thanks.