For shopping sites, online marketing is all about traffic and conversions. While paid marketing and ads have advantages, organic promotion is equally important. Link building for such websites is as important, because it ensures exposure, branding and engages the target audience.
If you want to make the most of shopping guest posting, a good idea is to hire a company that specializes in your niche. Ask them what they can do for your shopping site, and always place a small order first to test their services better. Link building has to be about content ideas and quality more than anything else.