Your local phone directory is a pretty good place to begin when looking for someone to design your portfolio site. There should be a good selection of design houses to choose from, so you will have a better chance of getting your site completed within your budget and time frame. A good design house should have specialized people in all aspects of web site application, from design to functionality to search engine optimization. Going into a design house with all of your portfolio information in hand and an idea of what features you want on your site will always assure you get a better estimate on prices and time frame.
Design house services are usually fairly expensive. However, that higher price should get you specialized people, purchase of your domain name, reliable hosting services and free updates for your portfolio site.
When you start looking up potential designers up in the phone book you will find a lot of design houses. They might be expensive but they usually know what they are talking about. They should have specialized people in all aspects of the web from design to usability to SEO. Going into such a place with your information in hand will always give you a better bid on your site.
A good design house should purchase the domain name for you, Host you on a reliable servers, and even make updates to your site – for a fee of course –