Like the sibling commenter, I recommend a $50 TINY7 quad as by far the most fun per buck I've had. It's indoor-only, as it's too small to fly in any sort of wind, but it's super fun and you can learn to do loops, tricks and fly over/under/through furniture.

EDIT: The UR65 the sibling commenter mention looks better, it's brushless, which means much better speed/agility.