While I myself use disposable Bics, I've seen high-end German electric shavers go for thousands and thousands of dollars. Frequency conversion might well be viewed as econonomical with such a razor.
Anyway, I'd suspect that a 60Hz supply would work just fine. A step-up transformer would do the trick, just make sure it's rated for the load of the razor. I'd suspect 300va or so would be fine, but that's just a guess. It should just run a bit faster on 60Hz, otherwise it should be fine. If you are looking for the ultimate in German shaving experience, well then a frequency converter might well make sense, there's certainly plenty of them for sale for traver purposes. While there might be some issue using them as permanent wiring, I'd think that worst case you should be able to install them in a metal enclosure or some such that would keep your local inspector happy
(you ARE planning on permitting your receptacle and having it inspected, aren't you? surely even the ultimate shave is not worth risking killing yourself or burning your house down for)
You should also install GFI on the secondary of the transoformer. GFI 220v receptacles are somewhat uncommon here in the US, but you can certainly find 220v GFI breakers. Make sure the GFI trip on your breaker is rated for 5mA (personnel protection) rather than 30mA (equipment protection).
The issue of center-tapped grounding is key, particularly if your razor has a metal case. You most definitely do not want to wire the metal case of your razor to 120vac. Make sure you figure out how the razor is meant to be wired.