Yeah, customer service at Whatbox is amazing. They're pretty good on space if you get a HDD
plan though. But they start at $22/mo. They used to be $25/mo. I've used them for years. Every time they upgrade their servers you get upgraded to the new stuff for free too. It's awesome.
You can't reasonably expect to get a seedbox for cheaper than the $15-25 a month range and you really need to be in the $20-25 range to have a decent amount of space. If you want cheaper than that then you're out of luck for seedboxes. Your best bet would be a VPN if privacy is the concern, and you can get those for pretty cheap. If you want something to actually seed at good speeds for you though, you're gonna have to plan to shell out a bit more than your range of <$10/mo that you're thinking.
The only other option would be finding a buddy or two to share a seedbox and each pay your share of it. A lot of people used to do it with dedi boxes from kimsufi (OVH) a few years back.