I think different people react differently to advertisement-like links. If the link is valuable to the reader, I think the visitor would definitely thank you for linking the site. My suggestion is don't be too eager to sell the link. And I think honesty is the best policy. Simply tell your visitors that you also have this e-commerce website. If they like your blog, they would probably go and have a look at your website. And of course, if they think your website is well-organized, they would love to read your blog and get to know more about you.