Where to sell my business?

Hello everyone. Long time no talk. I have a web development business that I would like to sell. I have around 20 clients and continue to get people asking to build sites for them as well as requests for web site updates. I started a full time job this week doing just SEO and I feel like I am going to stay there for a while.

My question to you is where do I sell a complete business, not just a site like on Flippa? The business is 10 years old and it has pretty good value. It has a PR of 4.