True, I was looking at the prices for higher end drives with on-board DRAM, but DRAM-less drives like that UD90 are also fine in the age of NVMe. Going DRAM-less was a significant compromise on SATA SSDs, but NVMe allows the drive to borrow a small chunk of system RAM over PCIe DMA, and in practice that works well enough.
(Caveat: that DMA trick doesn't work if you put the drive in a USB enclosure, so if that's your use-case you should ideally still look for a drive with its own DRAM)
(Caveat: that DMA trick doesn't work if you put the drive in a USB enclosure, so if that's your use-case you should ideally still look for a drive with its own DRAM)