I’m not sure what this means so it might mean the following, but I note to do a meaningful value-added study you would really need to control for individual and family characteristics that likely play a role in career outcomes. Examples along those lines include the Chetty study, Dale and Kreuger, and so on.
And really you need to control for self-selection as well. You mentioned COLA adjustments, which is definitely one important issue. But also, suppose more people in Major X at College A choose to go into government and public service, including education and higher education, and at College B more choose to go into for-profit firms. Then College B might end up with a higher median income for Major X graduates. But that is not necessarily because College B added more value, it could just be choice. And that gets complicated because maybe people choose colleges good for what they want to do, but maybe also contrarian strategies can actually make things easier sometimes (big fish little pond sort of stories). And so on.
To my knowledge, the data simply does not exist to sort all this out for every college on an annual basis. But for what it is worth, even with what I would consider to be a pretty incomplete set of controls, the above studies already suggested maybe there is a lot less value added for most graduates than many people assumed. As in, individual and family characteristics were really dominating college choice for most graduates with at least a fairly broad range of selective colleges. And I suspect if you really controlled for self-selection factors, the detectable value-added might decline even further.
Of course maybe if you were talking about very big “tier” differences, like Ivy+ versus regional and local colleges with low graduation rates, there would be more difference. And actually the literature kinda supports that, because they found that for the sorts of lower-SES applicants who might go to such a college if they didn’t get into an Ivy+, there was a bigger difference than for the sorts of higher-SES applicants who would just go to some other selective private or flagship public.
Still, I am not sure careful studies would find enough value-added difference to support anything other than very big “ties”.
Assuming you buy that (and a lot of people are still very resistant to the idea), then ROI differences within broad ranges are going to be largely dominated by: (a) actually having the program you want for placement into the career you want; and then (b) minimizing cost of attendance.
And even if you are not sure what to think about all this . . . a significant difference in cost of attendance is a hard, knowable variable. All this value-added stuff is very hard to pin down in any sort of reliable way. So to me paying a lot more for a college even when there is a less expensive alternative with the program you want is a pretty dubious ROI proposition, barring at least a truly huge difference in the nature of the institutions.