But a lot of that is going to be meaningless unless you have an idea what you're looking for or what's important. Talk to teachers and parents and get an idea what questions they want answered (or figure out what's important to you).
Quality is a qualitative measurement. There's no single statistic that will tell you how good or bad a school is. On the other hand, it's fairly easy to answer more fundamental questions: How many students graduate? How many graduates have the prerequisites for college? How many are receiving free lunches? How much are teachers paid?
SchoolData Direct: http://www.schooldatadirect.org/ has some great information related to school performance, including several metrics exploring the relationship between spending and performance. You can find state data here as well.