I'm looking to set up a small site for a friend that has some widgets they want to sell online. I don't think I will have much time for maintenance once it goes live (for that matter, I don't expect I'll have much time for initial setup and configuration), and I am looking for something that is dead-simple for a non-technical user to maintain (financial/payment info, add/remove/change products).
The second most important part would be good integration with a payment provider. I'm not too fussy what language it's in if it meets my other criteria (if I don't know the language I will learn enough to get the site running).
Also important is that I'd prefer to stick to open-source products, mostly because I don't think this project will have much of a budget for high-end commercial products (at least not until it makes some sales).
The last time I did this sort of stuff we were building custom sites from scratch for clients with very specific needs. I do not have recent experience with the current generation of blogging tools (Wordpress, Joomla, etc...) and I don't really know which off-the-shelf combo of platforms and plugins are best to get something up and running in as little time as possible.
Hosting your own online store is a full-time occupation, no different from running your own brick-and-mortar store. Anything that accepts online payments will be targeted by criminals for online fraud.
If your business is selling widgets and not running online stores, I strongly, strongly suggest using a hosted service with its own web integration and payment handling. I know people who have used both Weebly and Etsy and who are happy with them.