I know what these guys are talking about. I'm 14 year old girl and thrift stores are the best place to get stuff. Get reference photos so you know what you need like brown shorts or white dress shirt etc. You might even find something there and build around it. I found i giant thermometer shaped like a stopwatch so I became the white rabbit from alice in wonderland with a steampunk twist of course
You can ask family and friends to help but since being a teen you tend to be on a budget so check your recycling and use pop cans or something if you need some metal.