I design websites and consult on SEO. The important thing is to find a designer who you can work with and trust. They will make mistakes. The most expensive thing is getting "exactly what you want" leave that for companies like coke and pepsi who have money to burn.Instead of getting "exactly what you want" get a website that meets your needs and can grow with you. For SEO make sure there is more content (text) than code(HTML,perl, java). If the website looks exactly the way you want it probably won't be SEO friendly. Look for a SEO firm that has gotten others on the first page of goggle. If they tell you they will get you on the first page with one word key words don't wast your time. A new site should start with 4 word combinations and decrease it as the site picks up page rank. This takes 6 months to a year. For a small company, look for a consultant on the rise. Look for people who don't use jargon. There are plenty of good web designers.Everyone says they know SEO but only a handful really do.Make sure they understand what you are selling.
http://www.Killoil.com is a new site I started to sell advertising on. It was built on Joomla so that anyone can update it. my site is
http://www.netadvertisinggroup.com which has lots of good advice.
http://www.curaflo.com is a site I have gotten on the first page of google.