Etsy/Amazon type website template or packages?

[SimonMac]

There is a multi vendor plugin for WooCommerce. All of the Vendors share the same storefront.

Linky

I think NLUK wants to upload from multiple vendors to his tat shop

[ladymuck]

Is a tat shop the next big thing to have?

[BrilloPad]

Is a tat shop the next big thing to have?

A Simon Dolan jam shop.

[courtg9000]

I have used WordPress +Woocommerce a few times and commend the other recommendations of WordPress +Woocommerce + plugins.

I do sound one note on your cost base. You may need to research and factor in the cost of the pro or plus versions of these plugins as you may not get everything you need with standard or lite free versions. My advice is to research and adjust business plan accordingly subject to findings.

With that CSV import tool. It is a good tool - used it several times, you need to consider stuff that cannot be put in a CSV file ( product images, video's PDF's for example and how you will handle the process. - Do lots of testing!!
I have developed lots of sites in WordPress (lost count) from 2-3 pagers to several hundred products and lots more functionality.