Usenet wiki (unfortunately we don’t have one on Lemmy): https://reddit.com/r/usenet/wiki/faq
Two 1 TB blocks on different backbones for $15: https://portal.usenetprime.com/cart.php?a=add&bid=37.
3 TB for $15 (4000+ retention): https://billing.blocknews.net/signup/blockfriday
6 TB for €15 (2800+ retention ): https://www.bulknews.eu/checkout?product_variation=43&locale=en%2F and use the code bf241. Bulknews is on Abavia backbone.
4 TB for $25 (4633+ retention): https://newsgroupdirect.com/member/billing/?plan=ce57&planid=233&yes_tracking=1
500 GB for 10.50 till January 3 (3000+ retention): https://usenet.farm/
The retention might not be accurate, probably larger.
How does Usenet qualitatively compare to a seedbox, for people who’ve tried both?
I haven’t tried seedbox, but Usenet is very cheap and you can consider it similar to having private trackers I suppose. You will find many releases on Usenet that you will only find in private trackers. Also you don’t need seeders, so as long as the file wasn’t removed by DCMA you can download it.