I suggest you do a survey of your favorite photos shot with your kit lens and see which focal lengths are used. Then, think about what photos you would like to shoot but cannot with this lens (low-light, wildlife, macro, or those shallow depth-of-field portraits that prompted the Portrait Mode feature on the iPhone) Use that as your primary guide towards your next lens.
At the budget you quoted, the choices are slim, and I suggest looking at used gear. The Canon 55-200 is a kit lens zoom, and you should be able to find them cheap in great condition. A prime lens is a great choice too, in addition to the Canon 50mm you can check out the YongNuo 35mm f/2. The 35mm focal length gives you a similar field of view as in 50mm lens used in full frame. It is an ideal all-round field of view, but it may not be ideal for you.
I will also suggest the 35mm 2.8 Macro used. Don't know if you can get it for $150. You get the versatility of capturing close-ups. Don't bother with close -up filters or extension tubes unless you can get them for dirt cheap.