BioEconomist

Math people are going to do fine in just about any program nation wide. I would apply to some top tier schools, and just have fun. Maybe you always wanted to go to MIT? Give them a shot. Most departments will accept a good applicant from a different discipline, Not having a bachelor's in economics is not a handicap at the graduate degree level. Just make sure your linear algebra is strong, and your statistics. Just research to find the right fit. What interests you about economics the most? Environmental Econ, International Trade, Libertarian Ideals. I had a friend that started out in History, and then got a masters degree, and is currently working on a PhD in econ. He wanted something heterodox because of his biases in history. So he settled into the University of Utah, they have crazy theories and teach things like Marxist Economics, and other crazy topics. I did my undergrad there and liked it because I was exposed to ideas that I wouldn't have encountered elsewhere. The common slogan there is: "I read Adam Smith and understood him". Anyway that is a tangent. My point is figure out what you like about Economics, and go to schools that teach to your interests.

Remember that PhD student is a job like any other. And your application is a job application like any other; A track record of success is far more important than what you score on a test. If you have published before, then you are a highly prized applicant. I would be surprised if you didn't get into at least one of them. I got into a Phd program with a GRE score that was super low. I was surprised that they were willing to roll the dice with me. I only got a 720. That publication will pay off.