One of the most difficult questions to ask a client is what their budget for a particular project could be tasked to social media. This isn't just for social media, as the fear the client has is giving you a number and not getting the best value for their money.
I can understand this, but the truth is if your client doesn't trust you to do a good job with their money, then you shouldn't be at a proposal stage, especially for results-oriented social business. Social projects aren't similar to SEO or websites or television campaigns. They're based on large-scale adoption from a target audience (b2b, b2c, person-to-person). To create that kind of change, you have to have the trust of your client and knowledge of their company. At least, if you actually plan to make a difference.
I've been a social media consultant for business for five years now. My company has worked with companies big, small and micro, and when you add in the headhunting, you get a spread of experience unique to the field. I still believe that 80% of "social media consultants" have never taken a check, and the majority of the rest are glorified copywriters, but all that means is the talent pool for change making social media projects is still very shallow.
The challenge is not with the tools. Facebook is different than direct mail, but the results desired are the same. Solve a problem. Boost sales. Cut costs. Improve the company image so we can solve problems, boost sales, and cut costs because we are trusted. Hire more people. Give customers access to the information and people they want to talk to. Impress the media. Those are the metrics you should be looking for, and they directly correspond to the budgets you're trying to tease out of your client.
So here's a little primer to help you. This works primarily with small companies with a website and some kind of personal contact needed for a sale.
Social media strategies have to be tied into something bigger than social. I've always liked to connect them to SEO budgets. It's a small company focus, but considering the way the web has splintered the attention of prospects, the best strategy is to be everywhere they are.
Identify the organic SEO budget of your client (especially if they're small), and focus on either improving results or gaining visual share of the first page of SERP's. If your client is paying $500 a month, compare their current results with what you're promising. In many cases, if they're only paying $500, you can equal or better the results.
If they're paying thousands and the SEO company is good, you can work into a portion of the budget or base your fees on your results versus the SEO company. A bonus to this pricing strategy is you're working against SEO companies today, but will be hired by them tomorrow. Social is the next step for SEO. If comprehensive search actually means anything, it's a natural progression. Gain the skills to show in video, pictures, business, organic, instant, and other searches, and SEO companies will work with you to provide a consistent package to their clients.
Most important, you've identified your offering as a result, instead of an hourly basis. You want to get off the hourly billing as quickly as possible. That's fine for established industries, but social is new. Hourly is just a way to limit your fees to your labor. Think to the result, and you'll command a stronger profit margin.