To write an article for submission purpose and you will need to submit it to 100+ web-sites or just too little major ones. The costs for copywriting service start at 10$ per 500 words and depend a lot on eminence of the article. As for submission you can do it yourself or find actually cheap options, for instance you can submit to bulk sites for just 10$. What about results? You will have an article planned on hundred of sites, that tells about your niche, and you will have a link which points to your site. There are good chances that Google will treat this page and the link as helpful.

You can sprint a free link exchange with sites and get inbound links, but in this case you will need to spend your time in finding sites that are willing to exchange links with you, also, you will have to put a link rear to this site. An option might be buying inbound links, it is easier to find sites that will put your link for some fee, but characteristically you will need to pay for a link each month, which is not a good investment, unless you have found a very good site associated to your product's niche.