Another aspect of scratch building that has not been mentioned is the wood. If the model is being built with the intent to fly it, it will need to be built out of lite ply's and balsa wood which depending on what plane you choose can get into some money.  If it is going to be display only, then you might be able to cut up some wood in the wood shop for your parts. If you do build a scale model, please understand that as mentioned, it would not be a good first model for you to learn on. Good Luck, Dave