"About" is (probably) unnecessary. It is the same as saying, "Can I ask your name?" In this case, you just want to know the other person's name. If you say, "Can I ask about your name?" it means you want to know what the name means, if it has a particular family connection, etc. Asking the price means you want to know the price; asking about the price means you want to discuss why something is priced as it is (e.g., it is very cheap, so is it damaged or second-hand?).

You can also say, "How much does this cost?"

Just say, "Gimmie the price punk!" :P