My best recommendation, unfortunately, falls out of your budget. I personally believe Walmart bikes are a waste of money, and would rather see you save that $200 (use it for normal expenses while saving up) and buy something that will actually function well enough that you'll want to ride. I might recommend a recumbent trike over an adult tricycle. Not only will they be more comfortable, but they are generally better made. If you're lucky you can even find one used for under $1000 (and I promise, it is well worth the investment).