you can buy LTO tape drive like dell on ebay, just make sure seller will dump how many hours were written with device. when you will have device you will need to connect somehow to motherboard - for example you will need sas controller which can cost like 100$ on ebay. next step would be choosing os - you can go with debian like system or centos, on github you can find ltfs repository (if i good remember developed by ibm guy? please correct me if im wrong). neext step is buying tapes - good source is amazon, for example 30eu for 2.5tb lto 6 tape (included taxes). good luck!!

ps. about which lto drive you need it depends on your needs, if 2.5tb per tape is fine then go with lto version 6..

for more you can ask on r/DataHoarder