Welcome to the forum!
The cost on these carpets varies wildly based on many factors that include almost anything imaginable - age (20 years makes a difference), design rarity, color, quality of color tones, originality/condition/wear, provenance, tightness of weave (workshop rugs), repairs-restoration and the quality of. For 9x12 you could be looking at an 5,000 or 50,000 rug. Do you have additional photographs and information? As a rudimentary tool, the rug estimator can help. Someone on the forum once said something very accurate about this tool however - it does not have eyes!:
This would be a typical 1900-1915 Tabriz with not too many colors, light but even wear, maybe some selvage work
http://www.RugRag.com/Ap...-4C30-91F9-135B32FB4245
This would be a sample of an piece with characteristics of an older piece, a few more color and clearly natural dye. Some of the newer ones may appear natural but they really were early synthetic then washed.
http://www.RugRag.com/Ap...-409D-B6D0-A936D8EB93C9
The best thing to do is look at recent auction records through main auction houses, maybe see if there are notes on condition for similar design/age rugs and compare to this piece.