Contact the tournament director or one of the people helping. One of the best things about buying a tournament-used table is that you can actually try it before you buy it. You'll have an opportunity to see if it has issues. You could probably even get a couple of the more experienced players to help look for issues. If possible, provide your own transportation to save on shipping fees.
Keep in mind, the brand of table will be whatever they are using at the tournament. If it's a Warrior tournament, it will be Warrior. If it's a Tornado tournament, it will be Tornado. The Warrior will probably be a home model and the Tornado will probably be a coin-op.
I'm a Tornado player, but in the last couple of years Warrior has finally gotten their playing characteristics right. They have a good entry price-point. My biggest question on Warrior would be longevity. In a home setting, I don't think it would be a problem. In a commericial or high-use setting, the Tornado has the reputation of holding up even against abuse. That's not to say it can't be destroyed by idiots.
One of my biggest pet peeves is the quality and playing characteristics of the tables that the department stores sell. They do a disservice to serious foosball. I can picture a person, who doesn't know what to expect from a car, going out and buying a Yugo, then vowing to never buy a car again.