Think they are still available directly from Dr Grabow, contact them at:
Or you can call them at 336-372-5521
If that doesn't pan out I'm sure Paul's Pipe Shop of Flint, Mi has them, as her has a whole wall of Viking pipes for sale, and a massive inventory of NOS items.
Call him as his online inventory is only a minute fraction of his total inventory: Paul's Pipe Shop
There was a guy on Ebay selling Viking bowls-that he says were made in Mexico.Never bought one so can't tell you anything about fit or quality. Every now and then on Ebay you can find Viking sets-- one base with I believe four bowls in a plastic case.
The factory may have some-they were selling Vikings in one of their mail order specials last year IIRC.
The first generation Viking bowls will not fit the later versions but most you will see are the later version.