> This is where you hire a copywriter for your website and he or she fills the pages with cleverly crafted, delightfully delectable prose that oh-so-playfully sing and dance.
Prose is singular. The plural of prose is proses, though it's not frequently used. If you're going to chide authors on style, make sure you've got the grammar correct first. Also as a counterexample, I'd like to point out that woot.com typically exhibits playful prose to great effect. Honestly, I probably visit more for the excellent ad copy than any other reason.
Based on the grammar, "that playfully sing and dance" refers to pages. The grammar works fine.
But it's clumsy, and should be This is where you hire a copywriter for your website who can fill cleverly-crafted prose into pages that sing and dance.
Absolutely. I was recently considering an ebook about good web copy and read the following in the preview: "it's purpose is". That was a deal-breaker for me.
It depends on a wide variety of factors. (And, in general, the more willing someone is to offer you a no-questions-asked quote, the more likely it is that their writing is, well, a commodity.) If I were bidding on something like that, I'd want to know:
* Whether it requires any special industry/technical knowledge.
* Who your audience is.
* Whether the page is designed to convert, or just informational.
* Your future content needs.
I've charged as little as $50 for that kind of writing (to an audience of laypeople, as part of a larger project, with no effort to sell) or as much as $500 (selling a to a narrowly-targeted audience acquired through PPC spending, as part of a one-time project).
I do write this kind of thing, by the way; email address is in the profile.