One of the worst things you can do when shopping for online marketing services is making the lowest price one of your principal decision criteria. If you are a service provider one of the worst things, you can do is to try to be the least expensive provider in the market. Your potential clients will often believe that your service level matches your price level. And you do not want the clients that are looking to get your services at the lowest possible price.
I have learned the hard way that the clients that pay the least expect the most. They also tend to make more noise than the more expensive clients, and they will cost you more in materials and human grief expense than they are worth. You will then eventually get the joy of firing the client. One of the joys of being in business that you do not want to have to experience.