Nitai, glad to hear about a ShareCG store. I had several conversations with 'ShareCG David' a while back and we discussed seller requirements. Having content that installs properly was a main concern. I wrote an article in my '3D Digital Art Magazine' about creating Poser/Daz compatible zip files on page 5 and 6 of the Preview issue.
http://www.virtual3d.krown-products.net/modules/myiframe/index.php?iframeid=1/
I would highly recommend having something like this as required reading prior to anyone uploading either free or for sale items. It needs to be updated for the new Daz 4.x versions, but you get the idea.
It may be a good idea to require perspective ShareCG vendors to have posted a minimum number of free items before they can become a vendor, like 3 or more. It could also be based on end user product ratings, like getting a total of 12 stars.
Just my 2 cents.
If the commission rate is decent, I'd add my MeshWorks products to help get things started.
MeshWorks - http://www.krown-products.net/meshworks/index.php