You could start by spending $50-$100 on a nice WordPress theme to slap on the front end. Spend money on a designer when you've got some initial paying customers.
Probably the best use of money on an extreme budget, is finding a good one and then modifying it.
It wouldn't even take that - you can go a long way in a few days making a child theme of twentytwelve and tweaking the stylesheets. Nearly everything else is plugins.