More often than not, your followers on Instagram will post up an image showcasing your products that you'll want to use as a way of giving your customers social proof and a compelling way to see how your products are being used by others.
A reposting tool will soon be available natively on Sauce which will enable you to search by hashtags and account names to find content you can use for your brand.
... until then, you can use something like 'Repost' to achieve similar results as demonstrated by this account here: http://www.getsnapppt.com/instagram-shop-yoga
So, to repost someone else's content with shoppable links:
Download and install the Repost app
Browse your Instagram account to find posts you wish to use
Re-post content using the steps described in the Repost app
Sign in to your Sauce dashboard and open your 'Instagram Feed' tab
Select the posts you wish to use and add shoppable links to selected posts in the usual way
Done. Your reposted content and the shoppable links you've added will now appear in your Sauce profile page and shoppable feed embeds.