I just purchased black STi floor mats from Subaru of Gwinnett and I am glad I did. These floor mats don't make my car accelerate quicker or take corners faster, what they do allow me to drive without the aggravation that I experienced with the throw-in mats which would slide and bunch up in the drivers side floorboard. These mats come with two attach points for the drivers mat ( with a supplemental attachment bracket included ), and the mats themselves fill out their floor pan areas much better than the throw-ins that were included when I bought the car. It's a relief to be able to drive and mot have to dick around with the floormat under my feet. I should have done this a year ago.
Interior rice makes everything nice. The only downside to them that Ive found is if you want to fully clean your interior, you have to remove the bolt on the bracket. Whats nice is you can run with that mat still installed during an event because it is technically "bolted" to the car.
Eh I just go with disposable floor mats and zip ties FTW! My original WRX mats will still be pristine when it comes time to sell the car or whatever.
erm... why not just use them yourself instead of thinking the next owner lol? You can always buy more floor mats in the long run.