Memory requirement of Ubercart? I am setting up a shopping cart for a client and will host the new site on a separate VPS. What is the typical memory required to run a Ubercart site? We are targeting a few thousand users, around a hundred products, and under ten concurrent users.
Drupal 7 requires a minimum of 32MB (see - http://drupal.org/requirements/php) however in reality it will require much more, simple sites with a few contributed modules should be around 96MB.

Personally I'd recommend 128MB minimum and then tweak as required.

You can use the Devel module to output the pages memory usage to help you.