If you package them well, it shouldn't be an issue. The styrofoam-insert carboard box thing I was talking about should probably cost you like $10. See here. If it's worth the hassle of transporting the bottles, it's surely worth ~$2/bottle to protect them

Even if you don't do that, if you wrap them well with towels, T-shirts, things like that, it should be fine. As long as your suitcase isn't just the six bottles of wine, that is. But if there's some other stuff in there, it should be okay. I used to take a few bottles of wine back to university every time I came home for Christmas, summer, etc, and never had a problem with that. Although a few of those times were before the ridiculous liquid limits, so I probably took a bottle or two in my carry-on. But definitely would have checked at least a couple bottles each trip.