Phd

[Merlin]

Are you limiting this to US Universities?  I know a few people around on this and the sister board have taken degrees online at the University of South Africa.  They have a research PhD in Computer Science.  
https://www.unisa.ac.za/sites/corporate/...ce-(98803)
At less than $2k per year, you can't get much more affordable.

I saw that one but wasn't sure about its legitimacy. It is on my "to do more research" list.

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As you mentioned or If you don't mind a related field, University of the Cumberlands has a PHD in IT for $30K USD.
For some reason, all the programs I look at, if it's close to $30K USD, I keep it in my list of programs...
I can't afford any extra courses at this time, but if I had more cash or tuition assistance, I'll go for this program.
In fact, there are a few other universities that have similar programs, but it's not in Comp Sci, but in IT.

I don't know about the OP, but I specifically did not include doctoral degrees in Information Technology, Information Systems, Data Science, or Information Science, which are aligned with CS programs but aren't really CS.

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if looking at UK, then there's afew.

University of Reading has a PhD in Computer Science, it's about $39k USD for the whole program

https://www.reading.ac.uk/computer-scien....aspx#fees

University of Sunderland has the same thing, but cheaper, around $30k USD.

https://www.sunderland.ac.uk/study/postg...sophy-phd/

University of Leicester has a PhD in Management, with research areas in Information systems, User Experience and afew other fields. it's about $30k USD for the whole program.

https://www2.le.ac.uk/research-degrees/p...upervisors

Hmm... are those all fully online programs? I didn't find anything in the UK that was fully online. I found the Heriot-Watt online DBA/PhD in Management, but that was the only one.