Hi Glen,
in WAK1/WAK2 you have the tab "price planning".
There, you see all your articles. You can check all the articles you want to change. At the bottom, there is a button "Mass Maintenance". Mark column "Sales price" and click on the button.
Now, a seperate screen is opening. You there can enter you sales price in the field "Amount". Value has to be "+". Click on "execute".
All articles you checked beforehand should have the sales price you entered.
Hope it helps.
Regards
Tobias