Hi Phil and welcome! Dads usually worry about what their kids are spending money on until they convince themselves that you can be trusted not to waste cash and make sound purchases.
Books (such as Mark Wilson's Complete Course) are usually a good way to get around this problem as most parents think that books are OK whereas tricks probably aren't. The fact that you can buy one book with 40 or 50 'tricks' in it (in terms of ideas and how to make props at home) means they're a good investment. If you need to generate some Brownie points then volunteer to do a few extra chores around the house and you might notice that your folks will be a little happier about your Magic purchases! Bottom line is that you don't need to spend a lot of money anyway, use household objects, make your own gaffs and gizmos - virtually no expense required

!