I'm a big fan of setting realistic expectations with people for the hobby. So because of that, I can tell you that a 20 inch plane is mostly an indoor flying model. Anything but a calm day is going to toss it around like crazy and take all the fun out of flying for you. To get into planes that can handle a decent amount of wind your budget will need to expand significantly. The advice to get into a flying club is spot on, definitely do that if you can. In a club, you will get instruction on how to fly properly and you will meet other RC pilots who can answer your questions and show you how to set up your planes right. That kind of help goes a long way in being successful instead of frustrated. On the money side of things, have you talked to your dad about doing this hobby with you? Maybe you can mow some grass or trim hedges to make a few dollars?