We have hired lots of translators for all languages and they mostly use price/wordcount rule of thumb although some look at it and then estimate hours/days.
To find out what your competitors might charge, simply post a translating job on Elance and check the proposals. But ignore those quoting from countries that your language doesn't belong to because these can be using machine transaltion, ie: Google or other translating software. Also ignore middle men acting on behalf of others.
But not many translators are HTML savvy. There is nothing worse than receiving a translated web page full of MS Word font styling.
So if you can work with HTML, emphasize that and also the editors that you use, even if it's Notepad. Let them know whether you work with Windows, Mac or Linux file types and which editors.
Translation is piece work like any other piece work: by the word. 500 words or less there's a set price, no negotiation. 500=1000 words, another price. 1,000=5,000 another price. Anything over 5,000 is quo5ted by the job total.
Your question is "what do I charge?" and that you'll have to determine by looking at the competition, what the "industry standard" might be, and what you are willing to accept for the work.
Also recognize there are many levels of translation available and if you want to achieve the highest price make sure that you can do "natural and context" in either language. Makes a difference on what can be charged.