Modulo obvious demographic controls, Texas (K-12) schools' NAEP scores are slightly above the national average but, per-pupil, Texas schools are much cheaper than the national average. Following that last link to a big table of numbers, we see that Texas' savings come primarily from less spending on teacher benefits (health+retirement+...), though less spending on teacher salaries and administration also contribute.

One possible counterpoint: if we apply demographic controls to test scores, then shouldn't we apply similar controls to costs? That is, are Texas schools more efficient than New York schools, or is everything just generally cheaper in Texas? One quick and dirty way to reply to this question is to observe that Texas GDP per capita, which is about $48K, is only slightly under the national GDP per capita of about $49K, which in turn is not that different from the New York GDP per capita of about $51K (according to WolframAlpha). Meanwhile, Texas's education costs from that table are about two thirds of the national average, while New York's are about double the national average. For another potential control, use a cost of living index for each state, computed from the 2010 census: Texas is at 90, the national average is 100 by definition, and New York is at 125. Texas schools still look cheap with this control is applied.