take a look at the mechanism, the chime, etc and see if it looks like a reproduction, they are all over the place, but are nice clocks. Regulators are quite common. Even as an antique it's only worth about $150 - $300, unless rare.
it may be Asian? by: Ed
I bought a Star 31 day regulator similar to yours, which has 2 keyholes, clock and chime. It is Korean, with a movement by "Shewa". I had to fix the hour hand falling down, but otherwise it works well. If you ever remove the dial, it may be marked on the front of the clock frame.