Ignore the stuff about this not being a startup. It's you, striking out. Good for you.
That aside, what are you going to do to promote yourself over and above 99designs and co? It looks like a crowded market to me, so how will you make yourself stand out?
A couple of questions, if you don't mind me being very intrusive:
How many $249 gigs a month do you need to be profitable?
How will you maintain your margins as you (hopefully) grow?
Best of luck though with the site and service.