Perhaps two themes. But I will give you a very basic design of my ideas for the site. You create it (coded) based upon my feedback and get it setup on my server for me. PM me your prices and previous work.
Have you any idea what kind of themes would they be? if You are looking for the simple theme you could use one of the Free Wordpress Themes.It would save you few bucks.
Well its your choice but you can free wp themes to save your hard earned money. Visitors usually don't care much of the appearance. They need quality of the content. How solid is your content actually matters.