A few points before my price suggestion:

1. Your asking is fine.
2. Any offer within 10% of your asking is not a low ball IMHO. That is just a normal offer, esp on a high $ game
3. ALL of the high dollar games are tanking in price. The hard reality is that many of the collectors that entered the hobby in the past few years have filled their game rooms, still want the next new thing, and the secondary market is seeing LOTS of high dollar lightly used games for sale. Supply is going up and will continue to go up. I expect prices to continue down on these sort of games.
4. Every new game to come out will also impact the high dollar market. Lots of these more recent collectors always want to play the next new game. They need to make room and new games = more other low play games coming on market.
5. Probably the most important... 3200 plays is NOTHING. All that matters is condition. Anyone using a play count in negotiations is just trying to push it for their advantage. 3200 = bugs worked out and hopefully enough time for you to tune in the game so it plays really well. Condition is king. Is your game well maintained, any blems, any wear that is showing that would impact value? those are things that matter... plays means nothing other than a rough idea of mechanical part use. EVen with 20,000 plays, these games are just getting broken in. Many games in everyone's collection from the classic era likely has 100,000+ plays.

Now on to the fair price.

IMHO I would probably take 7500 for an easy sale if I were you.
Advertising at 7800, give it a few weeks and adjust from.
Also with these high dollar games you need to cast a wider net to reach more people.
Hit craigslist, Fbook market (and all the collector group pages also), letgo, pinside, and mr pinball classifieds.
Also put the word out to your local collectors. Decent chance that may bring you the easiest sale.

Last thought. Anyone buying high dollar (over 5k newer games) should be planning on at minimum a 20% hit as things continue with more new games and more supply of used games.

I think the biggest change we are starting to see is some of the more recent collectors with all high end classics, JJP, SternLE type collections are seeing the hits on resale, they dont have the stomach for it, and are getting out so a more rapid increase of supply of high dollar low use games (sadly these are also often lacking in an sort of maintenance or tuning in for game play)