GW inks have been discontinued....
Hate to say it, GW's line of inks have been discontinued.
But, on the bright side, they have released a series of replacements called Washes.
These are very much like the inks they replaced, but they tend to offer a little bit of color to everything that they are applied to. This is GW's way of speeding up army painting and still getting a decent job out of it.
http://www.games-workshop.com/gws/catalog/armySubUnitCats.jsp?catId=cat1030005&rootCatGameStyle=paints-tools#
That is the link to get the set for about $20. They really work well and can be thinned down to do panel line work and such.
Check 'em out if you get a chance!
-Mike