Depending on your state, there can be significantly more cost to creating an LLC - in California for example, it's $800 a year, plus the cost of startup (around $300.) Not to mention an LLC will not protect your assets if it's shown that the majority of operating income (or startup cost, I can't remember which) comes from your personal monies, and your officers must be actual officers of the company, not just your neighbor or family member who really has no say.
If you're seriously considering an LLC, ask yourself if you have enough business in the pipe for the year to justify the increased expenses, then consult a lawyer to fully understand the ramifications. Otherwise, shoot for a sole prop for the first year, then reevaluate after. HTH!