Here is a NYTimes piece from May which tabulates for some 170 colleges the average annual “net price” (i.e. gross cost less scholarships) for kids described as “mid. income”:
The figure for UChicago is $9,000, which is less than or comparable to that for most other schools, including many state schools (the University of Texas is $15,000; the University of Florida is $8,000). Only the most well-endowed of the ivies are by this measure significantly cheaper than Chicago (Harvard $5,000, Princeton $6,000).
Of course these are averages, but if they are at all applicable to your situation, @okeydokeypokey , the cost of a Chicago education might not be as daunting as at first blush the sticker price appears to make it. If your son has made U of C his first choice, applying ED would certainly give him an edge in realizing on that dream. If accepted, he ought to be prepared to do his own part in funding some of the additional cost, if any, through part-time or summer work - something I myself did throughout my college years and which I count as a real part of my education.
Though desirable, that might not however be necessary: the admissions policy at the University is “needs blind”, which means that once a kid is accepted, the University supplies such assistance as is reasonable in the circumstances of each family in order to make it possible. The Odyssey Scholarship program in particular was created for the specific purpose of relieving students from the necessity of taking loans or working. If, however, the financial package the University offers proves to be insufficient, I understand that that is a basis for further negotiation with them or, in the last analysis, refusal of the acceptance, leaving your son free to pursue RD applications at all other schools in the same way as if the ED application to Chicago had never been made.