Know-How Exchange : Social Media

I know this doesn't give you the input you're seeking, but it really depends. It depends on what it's worth to the client, the skill level of the people who will be assigned to the project, and a bunch of other factors. It also depends on how the client is going to measure success.

The "average cost" figure you are looking for probably doesn't exist, and if it did it would be terribly misleading. That's because it includes a wide range of client goals and expectations, a diverse set of skill-sets, different economies and industries, customers, and personal biases.

Your best bet: Specify the success criteria and what you're willing to live with as the cost of delivering that success. The client can always adjust the metrics if the cost is too high. This will also force you and the client to talk about the expectations and the desired outcome.

I agree w/ mgoodman, there's nothing 'average' here, but consider how many hours are going to go into the project on a daily/weekly basis (figure your costs) then mark up significantly. Be careful not to underestimate the hours or over estimate the results. It is important to establish goals and a plan from the outset otherwise the client may just start measuring FB fans and visits (since they will likely get the weekly update if they are originating admin) and, having little or nothing to compare it to, become less than excited.
Keep your rates high ... we all win!
:-)

So much of the answer depends upon the individual situation, objectives, needs, etc.. i.e., saying you're creating content, responding and monitoring is akin to telling a builder "build me a house" - you could get a $50k house or a $5M house. For example, how much research is needed to write postings? How many responses will you get? What form will the monitoring and reporting take?

On the latter, there are myriad tools for monitoring and measuring the social sphere - all with varying degrees of completeness and accuracy and different reporting formats. The free and cheap ones are not typically as user friendly, don't weed out spam as well and usually don't have the same drill down, tracking or reporting capabilities as the larger, more comprehensive and more expensive tools. Therefore they will generally require much more personnel expenses, versus a better, but more costly management tool.

The previous posters are correct - clarify objectives and output/monitoring with your client, then estimate your hours and structure a 'cost-plus' fee structure.

-Steve Udell