What I found really helpful was this app called Storehub.io, it sets up really easily and allows for pretty much most flexibilities that one may need when connecting Sage 50 to your eCommerce store.

I think they also have a B2B platform which caters for complex pricing, multi-warehousing and sales reps. There's a lot more to it, but definitely take a look at what they offer: www.storehub.io.

They've got a reseller program as well, which is cool for us developers/designers who are referring customers to them.