Here's the invitation

The location is not listed in the invite. Where will it be held?

Trump's Washington D.C. hotel.

The cost?

Guest staying at President Trump's hotel in Washington, D.C. during a Republican event being held there will be paying three times more than the usual room rates, according to a report published on Monday by CREW. https://t.co/7gPNPIcwfs

— Citizens for Ethics (@CREWcrew) November 3, 2019

More specifically, from The Hill:

The hotel's “premier” and “deluxe” rooms, the least expensive ones offered, cost $1,345 and $1,395, respectively, for the night of Nov. 7, the group reported.

By contrast, rooms typically average $455 a night, according to the report, which cites Google searches conducted Oct. 23, 25 and 28.

Who will be the featured guest speaker?

President Donald Trump

Among other topics, what will likely not be a part of his speech?

A discussion of the emoluments clause. As Laurence Tribe explained recently:

Emblematic of the depth of this concern, the domestic clause is absolute in character—without the foreign clause’s contingent exception for congressional consent—and expressly forbids even Congress from adjusting the president’s salary during his tenure or permitting him to accept any additional sum from any source.

Hey, maybe Shelley will ask him about it!

See also:

Mining execs to meet at Trump hotel where rooms will be $800+ a night