Only a minority of high-achieving, low-income students apply to colleges in the same way that other high-achieving students do: applying to several selective colleges whose curriculum is designed for students with a level of achievement like their own. This is despite the fact that selective colleges typically cost them high-achieving, low-income students less while offering them more generous resources than the non-selective postsecondary institutions they mainly attend. In previous work, we demonstrate that the vast majority of high-achieving, low-income students are unlikely to be reached by traditional methods of informing students about their college opportunities since such methods require the students to be concentrated geographically. In this study, we use a randomized controlled trial to evaluate interventions that provide students with semi-customized information on the application process and colleges' net costs. The interventions also provide students with no-paperwork application fee waivers. The ECO Comprehensive (ECO-C) Intervention costs about $6 per student, and we find that it causes high-achieving, low-income students to apply and be admitted to more colleges, especially those with high graduation rates and generous instructional resources. The students respond to their enlarged opportunity sets by enrolling in colleges that have stronger academic records, higher graduation rates, and more generous resources. Their freshman grades are as good as the control students', despite the fact that the control students attend less selective colleges and therefore compete with peers whose incoming preparation is substantially inferior. Benefit-to-cost ratios for the ECO-C Intervention are extremely high, even under the most conservative assumptions.