Pay in installments, get the words in installments. THat's my advice to anyone who wants to take up the offer. NFI if $600 for 10K words is a reasonable rate. Also a good idea to google the words contract writer sample.
http://web.law.columbia.edu/keep-your-copyrights/contracts/samples/25
For an example. There is precisely *no* situation in the world, where a service is being provided for money, that a contract written and agreed upon, is a bad idea. You state what you will provide, they state how much they will pay.
There are horror stories regarding every situation under the sun. A new account, with two posts and zilch else to his name, provides even less guarantee then normal of fair and honest dealings.