I've looked at the estorebuilder.co.uk website but I can't see any mention of the ongoing costs - i.e. the annual cost for the domain and hosting. I just see their terms and conditions that say that prices can change at any time. Do you know what you'll be paying for the second year?
If you're doing all that yourself, then it's really no different than someone getting a domain name and webspace and then putting ZenCart (free) or similar on it. I'm not sure I see what benefit this estorebuilder.co.uk is...