A couple hundred k to get engineering studies and permits to put a signal on the air. Then, a few hundred more to get everything in place for a real license. Yes, really. It would take years to get approval for a conditional permit. Then, you need to pay for tower space, STL link, remote control link, eas gear, and a studio facility. Even the small time operators spend thousands monthly for basic facilities overhead. I've seen it take months and thousands of $ to get an existing STL license modified to change the mode and azimuth.
I doubt there's space in Denver. Any "spaces" are there to protect other signals. Next, you'll ask about a LP license. It's virtually the same process, but you get some breaks on the magnitude of the studies required by the FCC. However, the decision to grant a license is based heavily on what you intend to broadcast. Typically, only churches and schools get a license. Maybe you could get a 10W license for about $100k. Or, they'll deny you and you're out 10s of thousands.
It would be easier to buy an existing station.