Hey Zhenjie... Thanks for your compliments! We've been working hard to continually upgrade and work on InstanteStore. Actually, we do custom jobs as well. There is a site called bigwoolly.com and we're actually the one that worked out the solution for them to set up the stores etc as well. So apart from hosted solution, we do work on custom jobs as well. We just need to know your requirement and we can work it out for you from there.
For enterprise customers, we will use InstanteStore as the "base" and make any changes/modifications necessary to suit the customer. It will be on a separate server or server cluster, depending on your needs. So, you will not be limited by what you see on InstanteStore.
We have our own group of designers as well if you need design help. Anyway, I will be looking forward to working with you, Zhenjie!
You can give me a tinkle anytime on our local number at 03-9015 9790. Or you can email pme directly. I do reply to my emails quicker than via this forum!