Four dollars a pounds is a good working figure for the price of gravure inks.
The 2001 report that I mentioned comes from an economic and
environmental assessment of the printing inks industry prepared by the
US Environmental Protection Agency:
The Effect of Ink Temperature On Solvent Losses and Print Quality
The table on ink and solvent costs and savings is on page 5 of the report.
You asked a very reasonable question, about the stability of prices,
and a good source turned out to be the company you had already linked
As you can see on this page:
the inks classified as "PF" are their gravure inks: "Temperature
resistant inks for flexo or gravure printing process..."
The PF price list is here:
with a price range in Euros per kilogram of 6.03 to 7.81.
Using the Google Calculator (one of my favorite features!), we can
easily translate to dollars-per-pound:
6.03 (Euros / kg) = $3.51 U.S. dollars / pound
7.81 (Euros / kg) = $4.54 U.S. dollars / pound
In a nutshell, then, current gravure inks from ichemco range from
around $3.50 to $4.50 per pound, so a nice round figure of four bucks
seems like your best working number.
Let me know if there's anything more I can do for you.
search strategy -- Google search on [ gravure inks price ]