I am seeing horses from 2500 - 25000 for a barrel horse, what is a good price and lines for a decent barrel horse?

I was thinking of getting a starter horse for my daughter to ride? what does better stallions or Mares?

I would not recommend using a stallion for a barrel horse EVER. Too dangerous, especially for kids. Rodeos have a lot of other horses and people running around, and even well trained stallions can get nervous/excited and act out. I personally only use geldings for barrel racing. They don't get moody like mares. A barrel horse can cost anywhere from nothing to upwards of over 50,000. If your daughter is just starting out and not sure she will stick with it, I wouldn't spend a whole lot. It all depends on her riding experience and what kind of rodeos she wants to compete in. Is this for fun at local family shows? Does she want to compete in something like the NBHA (national barrel horse association), or high school rodeos? And many people can claim to have a barrel horse for sale, when they haven't been properly trained. If at all possible, have someone who knows barrel horses to help you find one. Or contact a barrel trainer and see if they have a horse for sale, or could point you to one.
Many people are starting to breed horses for barrel racing. There are quite a few bloodlines that are proven winners in barrel racing, but there are many, many horses who are great and have no real specific bloodlines. Look at Scamper, Charmayne James' horse. He was from a feedlot and didn't have anything great on his papers, and he is a 10 time world champion, more than any other horse. It just all depends on the horse and the training.

You took the words out of my mouth. I agree 110%. Run2Win is correct about a stallion and with a kids around YIKES

You may check out your local high schools.. see if they have a rodeo team and let you know where the local arena's are.. You can usually find someone there to help you..and you may catch a good rodeo in the process!

I bought my barrel horse for $900, and she is very fast and very well trained. The price doesn't always matter. Sometimes you can by foals for over $3000. What you need to look for is a well broke, child-safe horse that is fast. Never buy a stallion for a child. Sure they may be well broke and calm, but they can quickly get dangerous with a mare around. A mare or gelding will do fine.