You can buy cheap traffic for your CPA affiliate marketing campaign from various platforms. You consider solo ads, where you pay to send your offer to someone else's email list. You also explore traffic sources like TrafficForMe or Udimi. You use social media platforms like Facebook or Instagram for low-cost targeted ads. You try traffic exchanges, where you can exchange views with other marketers. You can also buy inexpensive clicks from websites like Push traffic or Bing Ads with a low-budget campaign. You test different sources and track performance to find the most cost-effective option for your CPA offers.