Need help pricing my air suspension..

So I recently took off my AirRunner OTG kit and am trying to sell it but I don't have a clue what to try and sell it for.
I have been searching left and right for used "On The Ground" AirRunner kits on several forums with no luck. Would love to get some input from you guys.

Here is the kit in question: [url]http://www.airrunnersystems.com/air-suspension/on-ground-og[/url]

Thanks.

these don't come up very often (i've never seen one come up), and not a lot of people have copped this new to my knowledge. it's gonna pretty hard to price it, gonna have to go with your gut and adjust from there.

So msrp being 6300, deduct 10-15% for a hook up and then 20% for being used... I'd start from 4400 obo if no visible wear&tear.

Why are airrunner kits so expensive? 
What makes them better than say a BC coilover with UAS bags and an E-level for about ½ the price? JDM tax?