you consider yourself a Creative WebArtist, capable of Discovering New, Unique designs, that fit a customer in a way they feel you have made a original work of art for them, then consider this:
How Outstanding is the Quality you are providing?
Is your Quality the same as the Quality that the makers of the Chart provided?
if so, How does that chart translate into your Region / Currency / acceptance of prices?
if not, then What do you offer More or Less?
List YOUR unique POS Point of Selling (why would a clint choose you and not me? and add a little price for every unique good benefit they get from You!
Retract an honest amount of money for the things you are worse at, or are learning at, or think that others ( who made the chart) are much better than you.
Add the total up, take a deep breathe, and now you have something which is actually more valuable than a price: you have a unique list of things that CONVINCE a client why they should choose you and not others. 25% higher or lower price will not matter for a professional customer who needs truly your qualities.
LEGEND: Qualities can be anything: Flexibility, Experience, Charm, Friendlyness, Performance, Price, Honesty, Meeting deadlines, Delivering according to expectations of previous customers, Portfolio list, Client list, Design Style ( = personal and impossable to standardise in a chart ), Your age (if you are 65 years old, i might prefer to give it to someone who is mor elike 45, perhaps), your location, communication skills, size of company, amount of employees and variations of disciplines within your company/network. etc.
As you can see, PRICE is important but to most clients I have met in the past 12 years of my experience, just a small factor, really, and in no way a reference to a standardized chart, on a different country, by different people with different styles.
- Finally: chart what you feel fits your needs (its a good thing to be practical, even as a creative web-artist.