I bought used Grey Marble with Merkels last year for $500, so these guys are right. I don't think they're trying to be rude, just honest. That being said, when $400 is referenced, I believe that's typically the rock bottom that we've seen them go for. Yours is obviously in very good shap with low mileage, so you can likely get more. However, I think you're going to have to cut your asking price at lease in half. As has been mentioned already, there is a new model of Tornado out that is used in tournaments. To upgrade this table with all the new features (new men, bearings, sidestrips, etc.) would cost at least $200. Most people will to spend serious dough on a table are going to want those upgrades, so you have to factor that into your price.
I think your best bet may be to look locally, so the buyer doesn't have to account for shipping costs. Craigslist is a great spot, but another spot to look would be to find out if there's a foosball specific website in your area. A lot of areas will have a website dedicated to the local foosball scene in their state. If you're able to sell it locally without shipping, I wouldn't be surprised if you're able to get $700 - $800, but that would be tops imo.
Good luck with the sale.