If you want to advertise on Amazon or Walmart, you need robust product research. Helium 10 offers a massive database of products with seasonal trends, profit estimates, keyword data, and more. In addition, there are tools to help with writing listings and optimizing your listings for more sales.
Helium 10 pricing starts at $39 a month with a limited number of lookups on keywords and products. After that, the plans scale up to $249 with more features to optimize your listings.