Take your business to a niche where your competitors are no match for you. Take advantage of your experience and expertise. Make it cutting edge.

I write & publish Wikipedia pages, I charge around 3 times higher than what one would get normally from a freelance writer but the ones I create are not deleted by Wikipedia. With a history to demonstrate this, clients accept my higher prices and go for a page once that will stick rather than creating bad faith at wikipedia by going for non-compliant pages. This ofcourse involves real effort, expertise, technical know-how, a decade of experience, diligence and compliance from my end to ensure that it's worth the client's risk.

See how it fits to your business and how you can make sure that client is infact *willing* to pay your higher price himself rather than going for a lower priced "competitor". I put it in scare quotes because you are essentially wiping out competition and making sure that your competitors are no more your *direct* competitors.

You may already be there, but to relate that fact to the client and for client to be able to recognize and *appreciate* this, you would need to optimize your cover letter / sales pitch that does not delve into general promotional stuff about you - rather this should be a compact informative brief about what you can do which does not just out competes others, it makes them irrelevant for the client. As Jon Manning said, you will need to demonstrate yourself as a "5 star hotel" with actual work or credibility of past *clients* you've worked with. Once you've done that, the client will rather negotiate with you for hours to perhaps lower your price and finally accept *where ever* you take your last stand, but still not go to another provider. In anycase, it's an iterative process.