This'll depend on your businesses marketing goals, however, the most popular PPC network by far is Google Ads.
Both disciplines focus on getting your content to the top of the search results page. However, SEO does this organically whilst PPC requires you to pay for each click.
How much PPC costs for your business will depend upon the average CPC for your target keywords. This may vary month to month but can be managed and optimised.
A PPC, or Pay-Per-Click, campaign is the top level of your marketing content.  Having separate PPC campaigns for different marketing goals will help you target your audience and tailor your content.
PPC stands for Pay-Per-Click and refers to a method of online advertising, where you'll be charged for each individual click on your ad. You’ll find PPC ads primarily on search engines such as Google or Bing.