Yes I really do think MSA is your best option.  Do not let cost be a factor when you are chasing your dreams.  It's all about being happy, and if that means you need to do an MSA, study all day and get a 4.0 to land a Big 4 job or whatever you want.  Then it looks like that what you need to do.

Inspired, whether MSA would be good for you really depends on what you want to do long term.  I don't know that much about MSA, but I think it's a relatively narrow degree, good if you want to stay in accounting or audit.

MBA is much more broad and is useful in many different kinds of business and finance jobs.  However, as Dawgie said, only an MBA from an elite school is useful.  To get into a top MBA school, you need a lot of cash (well, the cash is not for getting in but for getting through), a high GMAT score, a few years of strong work experience, great employer recommendations, and great application essays.  Your undergraduate GPA is not that important.  However, note that you won't get much further accounting education at a top business school because most of them don't offer accounting classes beyond the basic level.

And if anyone here is interested in tax as I am, there is the option of MST, or cheaper and better for people like me who also like law and tax controversy, passing the Tax Court exam and gaining admission to practice in Tax Court.  That's what I want to do if I pass my last CPA exam (oh god, please give me a good BEC score soon so I can move on with my life!).
If you're interested, check out the discussion on the Differences between MST and JD thread here:
http://www.cpanet.com/cpa_forum/forum_posts.asp?TID=27369

As for my background, I am a former IT person turned tax person with a BA in economics and unofficial minor in computer science.  My first love was law, but I could not afford to go to law school.  I also liked technology and finance and had not been exposed to accounting until recently.  My college did not offer accounting classes.  I graduated into the dot com boom and had hoped to work in IT and save up a lot of money for maybe a decade, then go to law school and then do patent or corporate law, something that would combine my interests in law, technology and finance.  The dot com bust and other financial mistakes shot down that plan.  Three years ago, I went full time with tax after doing taxes on the side for a few years and becoming an Enrolled Agent, but it was very difficult for me to get tax jobs with CPA firms because I'm not a CPA.  For some reason, CPA firms think you are not good at tax if you're not a CPA.  That's why I had to go through this 3+ year ordeal of qualifying for and taking the CPA exam.