Allow me to quote what i said in another thread concerning sparks.

It didn't take long to deduce this simple solution:

I Proposed this -> { All equipment purchased with "Sparks" will receive a random stat augment applicable to the jobs that access user prerequisite. Example: Cloth armor sold from Sparks vendor with job listings for BLM/WHM/RDM/SCH/GEO/SMN could receive an augment of +INT or +MND based upon the level range bracket it's sold through.
New NPCs created that will remove any augment for the cost of X 100 the item's minimum equipment level. One placed in each city where sparks vendors are currently located. }

A NPC discriminates against items that have augments and will not purchase them with an active augment.