Congrats for ranking so quickly, if you are an expert of ppc, then continue coz google always ranks you when your site is new and if you dont follow its algo will drop you again... So be careful and dont use any tool for creating backlinks......
Just monitor your PPC. If it is making you money, keep it, if it isn't, drop it. All about the bottom line in the end.
everybody would love to use adwords because of its speed and effectiveness if not for the money issue. If you got it, buy adwords. If not, stick to organic seo....Takes way longer but you can achieve effective and long term results.
Still there is posibility that your ad will be visible on other websites also along with Search engine. Because Google Adword servs ads on Both website & search engine. You can try both SEO + Google Adwords.