Or should i just buy site-wide text links? I have seen many cheap blog posts around in DP and has thinking of trying it.. Will google penalise me if i buy blog post/text link from a blog of another topic? Any comments?
Buying blog posts won't hurt you, buying sitewides could hurt you, so I would stay away from that. Blog posts can be a tremendous help, if you buy them from quality blogs. Don't fall for the 200+ blogposts for $5, they generally don't do much good. You can check the blogs for registration date (a lot of them are re-registered with previous PR), backlinks and nr of pages indexed. If that is good, buy them and don't be afraid to pay $10-15 per post, they are the ones that actually help!
Wrote a blog post that will help you explain the effect of buying blog posts. Also if you decide to buy some you definetly need to read when to buy blog posts.
Blog posts can give you the best of the backlinks, as it is a contextual link! but then always buy blogposts in blogs of your own niche!! but then general blogs with good PR is ok. there are lot's of people who give free blog posts, you can try that also!