I agree with jblsmith. I do have all the courses required for a BA in math, some of them taken while I was getting my MA in econ, and there was still concern about my strength in mathematics. I thought that I had met the sufficient conditions for a PhD in econ already, but I'm starting to feel doubtful.
My admissions stats were shaky coming out of undergrad. I had a bad year, and my profile reflected it. Rather than apply to PhD programs (when I wasn't sure I even wanted to do the research), I opted to take more math and to get an MA from my alma mater. It turned out to be a wise decision for me because (1) I was accepted there, and (2) I was able to prove wrong some of the naysayers in my past. Since MA and MS programs usually have later deadlines than PhD programs, I might recommend you look at a few. Funding isn't usually as strong in those cases, but you can get a good feel for your future career, diversify your research areas, and boost those grades. And your GRE scores don't have to be as high. (When I took the test in 2005, I had 500V/660Q, and I got in without question.)
Also, regarding the GRE, I really hope you won't have to take it again. It stinks. But having a high score can help with funding at the lesser known schools, where they may need to boost certain enrollment stats to increase their rankings. If you don't like your funding options this year, I'd recommend taking it again. Shoot, take the test again anyway, and see if there isn't some extra money floating around your chosen school's graduate school. I'm sure you already know the quant section isn't really a math test. (The subject test is, and holy crap!) So many people from all over the world do really well on the quant section, and, in math/econ/engineering especially, you have to make yourself competitive with them. Many programs won't specifically say what their arbitrary cut off score is, but you can bet they won't be happy if you're below the 80th percentile (which is a score somewhere around 720). From what I read on the Kaplan site, your odds of scoring better on the test will significantly decrease once the revised version of the test comes out later this year. If you do feel like you're going to need to take the GRE again, start now. I used the Kaplan 800 Quant book (and the same for verbal). I also memorized values of common fractions/decimals/factorials and brushed up on my probability theory. That helped immensely. I hated studying for that test after I had "paid my dues" by taking the appropriate course work. Adcoms don't really care if you hate it or not. They just use the score.
Best of luck, MylesBaker!