I'd say you'll be a solid applicant without a masters degree. Dual bachelors degrees in math and econ are really the best you can do (without grad school) and your GPA and GMAT are solid. Work on an
statement of purpose and get the
LORs down and I'd say you'll be very competitive for schools in the 25-50 range (UC-Irvine would probably fall into that category, if not lower).
Try to squeeze in some research if you can. It doesn't have to be anything fancy, but if you could squeeze in some RA gig this summer or maybe in the fall, that'd go a long way.