Whilst I don't like Zen or OSC, (CubeCart developer here), I don't see an Open Source Shopping Cart as a reason to penalise a store.
I'm sure most of us are using Linux based Apache hosting probably with PHP/mySQL etc... (all free)
Other points are very valid thou - a newly registered domain, and no telephone number on the website.
Its a part-time business, probably drop-shipping. Returns could be a nightmare.
I'd prefer to buy from an established retailer with some technical back-up.