Gravers are an essential punchcutting tool. So far I've experimented with two brands: Vallorbe and Lyons.
Vallorbe gravers are considered to be the best available and are made of two different kind of steel: WS (tool steel) and HSS (high speed steel). As far as I know Lyons gravers are only made out WS steel.
HSS gravers are very hard and difficult to customise but carve tool steel very well. However, my experience with WS Lyons gravers is positive as well, they are softer and need more resharpening but you can work well with them anyway.
I haven't found an European seller for Lyons' gravers. Vallorbe gravers, on the other hand, are much more easier to get in Europe.
There is another European manufacturer that I haven't tried yet and seems to be good: Dick (http://www.dick.de/en/special-tools/products/gravers-and-punches)
I am purchasing my gravers and files in this 2 web stores: www.bijoumoderne.nl and www.cousinsuk.com (many other useful stuff can also be found there).
So far I have very limited experience with gravers, so contributions are very welcomed. I am specially interested in how to customise them to reach or work on special details. This seems to be fundamental in punchcutting.
See also:David MacMillian's TXT entry for gravers:
Gravers: Glardon / Vallorbe
Otto Frei. www.ottofrei.com
Champagne corks (for graver handles)
(But make sure they're champagne corks specifically, not just
wine bottle corks.)
BTW, there are inexpensive books on metal engraving that have valuable information to work with gravers and even manufacture them. I found this one concise but good: The Jewelry Engravers Manual (Dover) > http://store.doverpublications.com/048628154x.html