Sounds like you don't really need a dedicated spotmeter, but you might want a flash meter capable of incident and reflective readings.

The Minolta flashmeters are a good choice. I like my old Minolta Flashmeter III, which is simple and accurate and good at handling low light levels, and the IV that Michael recommends and V are good too. The new VI doesn't accept all the accessories of the older ones, but it has a built-in spotmeter, so those accessories like the 5-degree finder aren't really as necessary. Later versions have more features like calculation of contrast ratio or storing multiple ISO values (handy if you switch between two film types, like Polaroid and transparency), but like you, I do these things in my head, so I haven't felt a need to upgrade from the III. The new VI doesn't accept the Booster II unit, but unless you shoot large format or through a microscope, it's probably not something you'll need.

Sekonic is now making some nice flash/ambient meters that compete with Minolta, so you should look at those as well.