Web-to-case for a lookup field

I almost chose web-to-case as the simplest solution for students to be able to submit, from a page on our website, info about the college they are attending (we grant scholarships to college-bound students).

Then I realized that we store this info as a lookup field to Account (the college financial aid office) on Contact (the student)., but when a web-to-case record arrives, our scholarship manager staff person has to look at the "College Financial Aid Office" custom field on Case (with their human eyes), then choose the corresponding record in the lookup field on Contact.

It would be great to be able to offer a "picklist" of colleges to the student on the web to case page, that can be turned into the corresponding Account record in the lookup field. As in, the Student chooses "University of Oregon" from a picklist on the web page, and when the case record arrives in SF, somehow the "College Financial Aid Office" field on Contact gets filled in with University of Oregon's account record ID.

I know that Web-To-Case can generate a picklist field, but that still requires staff intervention to get from there to the correct Account record.

The colleges that students choose are almost always (but not always) already an existing Account record (created because students in previous years have already attended those colleges).

What are my choices for solutions here?

Additional goals:

* As little customization as possible, for easy support in the future (when I am not the admin someday).

* Low cost (or free, of course)

I'd lean toward a solution that has less tech, and pay the staff cost of a bit more manual human intervention - I am looking for a balanced approach.

If web-to-case with some human intervention is the way to go then so be it - I just want to suss out the possibilities first.