I'd recommend using something like Instapage (or Optimizely) also, in the following way;
1. Setup a basic landing page template on Instapage (or similar) for one of the products you wish to buy.
2. You'll then be able to copy this template and update the text, SEO elements and images for unique each product.
3. Ensure each of your landing pages has the following unique elements;
a. Unique page titles, e.g.: Sell Fast Furniture Online | XYZ
b. Unique h1 headings, e.g.: Sell Furniture Online
c. Minimum 50% unique page content: for example, if each landing page has 200 words of content (including headings) ensure that you each individual landing page has 100 words unique to that page only.
4.When writing content for your pages do the following:
a. Use the Google Adwords Keyword Planner and research other ways people search for your service, e.g. "sell furniture", "furniture sales", "people who buy furniture", "where to sell furniture", etc.
b. In your content ensure you use variations of these keywords, this will help keep your content relevant to all the ways people might search for you, and also helps Google understand the true purpose of your pages.
This should ensure that each of your landing pages is unique and won't be considered spam or duplication.
Obviously there are many other methods and techniques, but this is a good starting point and will be reasonably fast to setup.
The next step beyond this would be to look at link building and content marketing to encourage other websites to link to yours - this will help Google to identify your website as a source of trustworthy information. There's a heap of good link building experts on Clarity, so it would be worth chatting to one of them at some point once you reach this stage.
Best of luck