I just started juggling and made my own balls out of flour and balloons, but was wondering what a good starter set for juggling balls
I’m only a dabbler, so I haven’t used many different types of props, but I can wholeheartedly recommend the balls made by Sport Juggling Company. Mine feel great in the hand and still look brand new, despite thousands of drops.
Go to ikea, look in the kids toy section (pretend it’s for your nephew or something) they have a juggling set with beanbags, clubs and rings
I am a recovering juggler 
In my old juggling club (the “Several San Diegans Who Juggle Juggling Club”) Our standard beginner juggling balls were 3 old tennis balls. Carefully slice them open for about an inch or more on the seam with a razor knife. Fill them with popcorn or rice, and glue them back together with rubber cement. They have a good weight and they won’t bounce away when you drop them.
Make some Russian balls. Or buy some. They are great for beginners.