I would invest the money in content first and theme second. But the answer to the question theme vs content isn't always black and white. Depending on the niche, you may need a quality theme for the beginning; so that, your site is taken seriously. It's also possible to start with a quality theme and build out the content over time.
But look at it this way ... Let us say that you have a restaurant with the right ambience. However, the food is mediocre at best. You may end up making less money than a guy with great food in a low budget storefront.