My LGS recently got me in to have a look at building some custom systems for them. I looked at what they needed and was like:
> Hold up. You can pay me thousands of dollars to build something custom, and it will inevitably have on-going maintenance costs and high associated monthly costs for hosting + third-party API access (not amortized across multiple stores/clients), OR I could set you up on Shopify and a bunch of well maintained plug-ins.