As I tell my clients when I'm being tactful, I think your budget is a little light for what you want to achieve.
Like everyone has said, DIY is an option IF you're willing to invest the time to a)learn what needs done and b) DO what needs to be done. Because I started my business having been laid off with a day's notice in the height of the recession, I built my own site and wrote all my own content (all on WordPress). I finally reached a point where I felt the look of my site wasn't consistent with my branding, so I hired a firm to customize a template for me. Where I saved money is we kept the directory structure exactly the same and I moved 2-3 years of content right over.
There are several paths to get where you want, but as tony alluded the first thing is to decide exactly what your goals are for the site.