Please be careful with content that's not written for you specifically.
I've had clients in the past who've subscribed to a service that would provide blog post text to multiple companies, meaning the same post could appear on dozens of websites in the same industry at the same time.
Apparently, the once feared "duplicate content" penalty on Google is not as fearsome as some people previously claimed. Your website probably won't be delisted or punished for publishing something already published word-for-word somewhere else, especially if it's not in your geographic area. But neither will generic content bring your website much SEO benefit either.
The key phrase in your question is "high quality," and most private label content I've seen sounds canned. Even if your customers don't figure it out right away, they'll sense that you didn't create the content just for them, which is what Web visitors increasingly expect these days.
If you can afford it, better than buying canned content from a vendor is to hire a writer to create content just for you. And if budget is an issue, then go for quality rather than quantity. Five blog posts ghostwritten from your POV and with at least some of your special touches will be more valuable than a series of a dozen generic texts that could go up on any physical therapy or sports medicine site online.