VIPStephan had some great tips, and I'd just like to add on to it. I have established myself, and have accidentally attracted more than I can handle. One reason is that I have attempted to specialize in an area. Yes, its good to have a wide set of skills, and I use them, but I really focus on promoting myself as a developer with a certain CMS. I am active with it, discuss with other developers who use it, and find ways to engage with the project (open source). This also helped me to develop a reputation among other developers, who have on more than one occassion sent quality work my way. Establishing yourself as a specialist is generally better than a do-it-all type. It also narrows the field when you are looking for jobs, and you can really focus in that niche, spend less time on jobs which a lot of people are going for, and find a better pricing model that fits that niche.
I also find that when you put a quote out there, and you are afraid about overpricing, its generally insecurity about your own skills. I have found its much better to do as VIPStephen says, come up with a method for producing a quote that has breathing room. I put together a quote that has everything they request, but if I see them as a client with a tight budget, I may suggest things to cut or change to streamline the process. For example, does the client really want a Flash introduction to their website? I try to convince my clients that it is a bad idea for usability and generally not worth the investment. So if their budget is reasonable but not flexible, I suggest ways to reduce the project. If they claim your reduced budget is too much, then they are likely never to be happy with the price and its best to walk away. A lost potential client is better for you than a client that ends up being unhappy, and still doesn't want to pay. Its better for them too, as if one side is unhappy both sides are unhappy. The best tool is knowing how fast you work, and if you really can't put together a project quote, perhaps try an hourly rate?
A reputation isn't everything. I work exclusively for people I have never met in person. Each time I contact someone about a project or am contacted about a project, its an opportunity to build that reputation with them. So build your reputation with each client, don't ever belittle yourself. I've seen a lot of posts that say things like 'I have expierence with X Y Z and have no projects currently.' The problem is that it sounds like nobody else wants you, so watch what you say, and how you say it.
jeremy - gnomeontherun
Educated questions often get educated answers, and simple questions often get simple answers.