What is one of the best ways to get backlinks from related blogs? Comments! Leaving comments on blogs that are in the same broad niche as yours is a very powerful way to get your own blog to have some of that lucrative search engine traffic that everyone loves. The more you do it, the better the results you will see. In some cases, Google and the other major search engines will rank your blog very quickly if they see this type of pedigree backlink.
Gustavo Woltmann.
just buying, no one will backlink your site, you are not a trustworthy source, not a wiki, not some well-known brand.
the only thing, people always will keep with the source is posts with news, to avoid any problem if something wrong with their post.
really, no one will backlink you without any important reason.
the only way is to buy or exchange (but if your DA is low, no one with higher DA will backlink you).
but even if you buy, it will not guarantee anything, because the blog owner can remove your link one day.
just choose the right (keyword) domain and write at least 30 good SEO-optimized posts... and then write a good 20-100 posts without focusing on SEO, just write with simply readable language..
All free services with free backlinks are the worst thing and they will only damage your SEO..
If your site is informative, then get backlinks from the wiki... I added there a lot of links to my sites and after 2 years all links are still there...