Sierrastone by Interpace : Idlewild dinnerware set

I have nearly a full set of dinnerware dishes marked Sierrastone by Interpace. The pattern is Idlewild. I have been unable to find much information online regarding this set and am curious as to it's value and/or any other information. If anyone out there (that includes you, Googler) knows anything, any information would be greatly appreciated.


The bottom of the plates read:

Sierrastone
FINE QUALITY DINNERWARE DESIGNED FOR COMPLETE SAFETY IN YOUR DISHWASHER AND YOUR OVEN...MICROWAVE, TOO.
© by interpace
FKT JAPAN
Idlewild

The book Franciscan: an American dinnerware tradition By Bob Page, Dale Frederiksen, page 145, states:
"Sierra Stone Line
A new line of shapes appeared circa 1972-1975 called Sierra Stone. Oddly, the backstamp says INTERPACE but not Franciscan. The lines never appeared in Franciscan literature or catalogs, thus there is very little known of the line."

There are 8 total patterns in the Sierrastone line including: Idlewild, Sachet, Petula, Sunflower, Rimrock Gold, Rimrock Blue, Rimrock Sage, Rimrock Terra Cotta.

As listed in the above mentioned book, here is the piece type checklist:
Bowl, cereal, 7 3/4 inch
Bowl, sugar with lid
Bowl, vegetable round, 9 1/2 inch
Creamer
Cup & saucer
Plate, bread & butter 7 1/2 inch
Plate, chop, 12 inch
Plate, dinner, 10 1/2 inches

I have a 33 piece set consisting of:
6 cereal bowls
1 sugar bowl with lid
1 large veggie bowl
1 creamer
4 cups (1 without a handle)
6 saucers
6 small bread/butter plates (1 with chip)
1 large chop plate
8 dinner plates (1 with chip)