You are saying that you wanted to swim but don't want to touch water. Your website design is something which attracts the readers. You should select such theme which makes your content pleasant to read. Premium themes gives professional look to your website. Most of the time when you go for premium theme, it take care of SEO(comes inbuilt with the theme). However, you will have to pay minimum 8-10$ to get a WordPress premium theme. Some of the best site for premium theme is mentioned below. Check it out:
Themeforest is one of the best site that deals in WordPress theme
Some other websites are DIYthemes, StudioPress but they cost more than 50$ but provide better assistance than any other websites. It is highly recommended that always start with best premium theme because once you have built the trust among the reader with your contents, it will be much difficult to switch to new design or theme. While doing this switching you may loose your trusted readers because they will feel disappointed to see blank pages while referring to your website.