If your looking for a one time payment of under $100 then I suggest Sony movie studio. I have it and its is really great!
Although since you brought up $50 a month, I would recommend Adobe Premier, which is arguably the best video editing software to date. It is the industry standard, and is used widely by professional video editors. Adobe allows you to use this software for $20 a month through creative cloud as a single license. While for $50 a month you can get the entire creative cloud suite, which includes Adobe Premier, adobe after effects, adobe flash professional, and pretty much every other adobe creative software.
It's an excellent package that I recommend. I have a creative cloud membership for adobe flash professional ( their animation software )