Finally something I know something about, I'm just a newbie when it comes to web design, but when it comes to sales I have been selling since I entered the workforce.
I don't see your problem being a matter of charging too much. The best price you can give is the one that makes both parties happy - and sometimes that is not too easy. You must consider that sometimes the customer can be happy with a price and you not so happy - do you think that your work would reflect that? Of course it will.
You must always qualify your customer's needs and realize that sometimes if they are price shopping only - you are not able to provide them with what they need (ie the lowest price). Anytime you are selling a product or service - it is not unlikely you will only close 10-20 percent of the deals. With that being said - always qualify your customer and don't spend too much time working on the same guy (who is price shopping) when you can work on a guy that will see the benefit in the work you do. Read a negotiating book by Herb Cohen - he's the master at that.
So to conclude - decide what makes each situation a win situation for you - and in the end you will be happier for it. Forget about price - if they buy on price alone - they'll get what they get.
I hope that helps.
I need help, but I think I'm beyond help.