Lucky for you, there's no shortage of fashion bloggers on the web. However, their writing styles, reliability, and fees will vary drastically. More often than not, you're going to get what you pay for. Here are the 4 tiers of writers out there, how you might find them, and what a pay structure could look like if you hire them.
Fashion Bloggers with an audience - These are bloggers who reach a
sizeable audience, both on their site and usually across other
platforms like Twitter, Instagram, etc. They write with an authentic
voice and might already have deals in place with brands to produce
sponsored content. You could build a roster of bloggers like this to
either syndicate content on your site OR contribute regularly.
Depending on who you find, you'll have to compensate them with a
combination of either free product(s) or high fees ($200+ post).
Fashion bloggers without an audience - You can probably find dozens
of fashion bloggers who are passionate about the subject of fashion
and have a decent ability to create content for the web. You might be
able to source these writers by searching for certain hashtags on
Twitter/Instagram like #NYFW or #fashionblogger. Email them and ask
if they'd be open to writing for you. Just the fact that you're
reaching out and asking might be flattering enough where they'll say
yes. If they ask what you're willing to pay per post, start at
$75/post for 500 words. If you don't get any bites, bump up the rate.
Freelance copywriters - Trained journalists and copywriters should be
able to produce decent content for your site, despite their lack of
enthusiasm for fashion. You can write a job ad and post it to sites
like Craigslist, TaskRabbit, Elance and Odesk. I'll warn you in
advance though, that you'll wind up sifting through a lot of very
unqualified resumes and poor candidates. That said, this would be
your cheapest option in the sense that writers on these sites are
sometimes willing to bill at $20/hour.
Last but not least, you could create a part-time or freelance based "content editor" position for your business and put someone on a monthly retainer to produce X number of posts per month within your set budget. Businesses try to do this with interns, but often they require more handholding than its worth.