Something permenant, with supplied utilities (power+hvac+data), secured behind locked doors, with a reasonable view of the sky, on a university campus .... you are pretty near to 100k before spending a dime on the actual hardware. And then double every number if you want it under retractable roof/cover of some sort.

One-off temporary or unofficial rigs on rooftops can be cheap. But a system of installed, standardized, telescopes on university campuses won't be build on a shoestring. If you are going to do it, get the lens that makes it worth the while.