I've been doing some research for a client on B2B eCommerce solutions. Key needs are:

- strong shopping cart
- ability to have centralized product catalog that can be used for multiple regional and different language sites (eventually)
- ability to enable configurable products (that is, have base product, where some options are available, and others are not based on other option selections, etc.)
- ability handle multiple payment options -- credit card, PO, paypal, etc.
- ability to enable customer quote request generations

Currently the volume is low (have an existing site), but want to grow. When that happens, integration will be necessary, but not now. Integration would be on three fronts when its needed:
- user authentication / single sign-on
- into CRM applicaton for sales lead management
- into order fulfillment process

Lastly, would like something that could be done as a hosted/managed or SaaS solution as well.

Thank you in advance.