Blogging is a way of building the inbound links. How?
You blog, about interesting topics (link bait). Then you put comments on related and relevant blogs with a link to your blog / articles. You submit your RSS feed to wherever you see fit, and you submit your blog to the blog search engines.
Outsourcing Blogging or not - you need a blogger who understands your (target) market and your niche. A local blogger will write in a local language, about local topics. That is far easier to read (especially in a blog) than a PR structured articles released by the professional PR agencies.
Blogging Costs - an hour or two a day to start with. That will give you a meaningful (measurable) results in a month or two. You need to decide what your targeted SEO result is. In a number of relevant visitors per day. Relevant meaning, that come from the search engines for the phrases you want them to come (relevant to your business). Scope depends of the size of the market. Google.ie is much smaller than Google.co.uk, that is much smaller than Google.com. Therefore it is most likely (depending on the industry or niche), that you will achieve much more in a smaller market with the same budget.
Invert Pyramid – Writing for the Web