What area are you in? Are there any schools that have part-time programs?
I'm looking at this one:
http://www.cs.illinois.edu/online/programs.php
I don't know if my work experience will make up for having no compsci bachelors courses on my transcript.
The prices are crazy steep, though! Wah! It's online, though.... A friend of mine says that this program has a really good name, though... not that the entrepreneurs here would care about that. ;)
(Baby steps to the class... baby steps to the bank... baby steps to the bank...)
IMO, look for a respeced program that happens to be online vs. an online school that happens to have your masters program.
PS: While James Madison has a fairly large campus they only offer this program online.
UIUC has one of the top ranked CS departments. You should already be aware of the rankings and each program's specialization before making this kind of investment, otherwise you might end up spending a lot money and time on something that you'll regret.
The last time I checked, there were a number of highly ranked CS departments that offered online courses, the UIUC program being among them. Sometimes they only offered a special degree, others only offer online classes for a certain specialization. The acceptance rates also vary dramatically, but they'll always act like they are highly selective. There have been multiple times that I've learned of supposedly selective programs (in CS and other fields) that actually have extremely high acceptance rates. Other times a program might have extremely low acceptance rates, though, so it's hard to tell.
FWIW, I was in an MS program that was mostly paid for by my employer, but decided to do startup work instead, partially because I wasn't happy with the program. I'm glad I took the classes I did, but I wouldn't have been happy had I paid the full tuition.
Some things to consider are the dominant platforms and languages in a particular program. Some schools will teach coursework in something like python, but it's much more common to find schools dominated by Java, C++ and Windows (with profs/instructors refusing to deal with anything else), so if you don't like those environments, you'll need to be more selective.
A BS in Comp Sci would basically put you on par - from the perspective of those only looking at what degrees you have - on the same level as a new college grad. And you're close to a decade beyond that.
Anybody can learn how to code, but by going through the Bachelors degrees in Maths or Comp Sci you gain the theories behind it. Ofcourse, you might be able to read these books on your own and thus prep yourself for a masters degree. Moreover, if you are not from a CS background the university will force you to take the CS core courses which give you the foundational theoretical knowledge.