It's a matter of "Horses for Courses".
If you want 100% perfect English grammar there are generally only 2 options
a) Pay an educated Brit or North American around $10 / 500 words
b) Do it yourself.
The drawback in both the above cases is the "creative" limits.
How many different articles can you write on "Car Rental" or "Liposuction" ?
Once you manage 3 you'll be pushing the envelope to think of something new to say.
The alternative is to accept article quality that passes the test of unique ( Copyscape as an example ) and is "readable" but not totally grammatically perfect.
Most articles written by non-native English speakers are in the "readable" class, and you can expect to pay $1.50 - $2 per 500 words.
Providing they are "readable" ( not total gibberish ) it is very unlikely the SE algos will penalise you for using bad grammar, and there is a school of thought that insists even gibberish is better than nothing, provided no "inspectors" come visiting.
You only need to read some of the posts and comments on high ranking "pop" sites (music and fan for example) where totally unintelligble street argo is the norm to wonder wether gibberish is "kool".
So .. If you need lots of content you need to think "automatic content generators".
Because there is only limited control over the assembly of the output you will get some articles that are perfect grammatically and some in the "readable" category.
The advantage of automatic content generators is the speed of output, and in the case of Spinblitz the automated posting functions you get after creating the output.
It creates unique spintext articles which get stored on your PC.
The output can be in several different formats like .txt, .html, SENUKE, LFE or PLIGG, which saves you hours of copying.
The latest version has 2 Wordpress posting functions.
Then you can choose to post either POSTS or PAGES, selecting how many "spun articles" to post, over what period and what frequency.
Obviously to post on WP, you need the Wordpress blog to start with, but the rest will work with any type of new or old domain.
You can try it out free at :
http://www.spinblitz.com