Have a look at
https://bit-pay.com. We have a basic shopping cart feature that doesn't require any programming or hosting of bitcoin. We also have a payment API that makes it easy to integrate with shopping carts (and ZenCart is one of the ones on our list to do).
That seems like a good solution. I applied for an account and already got accepted. I will work on the shop and as soon as there is ZenCart integration I will make it available to the masses!