Yeah, I picked up my "kid hauler" from play it again sports for around $50 and it had new tires on it. I can't remember the brand off hand, but it was the higher end models that the big stores sell (wally world, target, etc..) and I remember that it cost about $250 new.
My only complaing on mine is that it attaches to the rear with a compression style fitting that you have to use a wrench on to put pressure on the fitting and their is a safety strap that must go around the rear fork in case the compression fiting falls off the fork while riding. Well, the strap has gotten caught in the spokes a few times and other than an annoying rubbing noise that forces me to stop and pull the strap out no damage was done to bike or strap. Did have the compression fitting go loose once when my wife put the carrier on her bike and didn't tighten enough. Also make sure to put a couple rear lights on the carrier and prefferably the flashing style and of course a big flag to draw more attention so cars coming from behind will see ya.
If i had to do it again I would buy one of the models that can convert into a 3 wheeled stroller of sorts and has a different style of attaching to the bike (a hitch or something that requires no tools and is quick). I have thought about modding mine to make it a quick connect/disconnect, but my daughter is getting too big for it and I will soon just get one of the tow behind single tire type of "bikes" that attached to your frame or seat post.
Also, if you have carbon anywhere on the rear of the bike (my rear supports and my seat post on Allez Elite) foreget about any type of carrier or kid attachment. When I was buying my bike I saw a guy bring in an identical Allez Elite that had the rear forks and supports totally destroyed ( i mean ripped off the frame for the supports and the forks were bent) because he attached a kid hauler to the rear. Me I use a cheap wally world my bike for the kid hauler duty and leave my road bike as a road bike and keep it away from the kids.