It depends on what you're after and what you're using it for. I broke down the costs I forecast for myself over the next decade at https://andrew-quinn.me/digital-resiliency-2025/#postscript-... and found tarsnap is unlikely to cost me more than 50 cents for my usecase. Backblaze B2 will cost me about $70-80 over the next 10 years, but it has many orders of magnitude more data to back up.

The cheapest I can find for a consumer buying e.g. 20TB Seagate hard drives and rotating them every 3 years or so is about $5 per TB-year, without mirroring. So if raw storage cost optimization is what you're after that's what I'd go for to start. Even AWS Glacier doesn't come close to that, although you do get other things with it.