Can I sell an item and have the proceeds benefit my fundraiser?

YES!

We call this "A Donated Listing."

After you create a fundraiser any "regular listing" can then be donated to
your fundraiser. The proceeds from the sale of the regular (donated) listing will then be reflected
in your fundraiser balance.

Donation Manager is the tool that is used to manage donations between regular
listings and fundraisers. After creating a fundraiser every regular listing will have
a Fundraiser Donations option. Click on the Fundraiser Donations option found in:
Listing Tools => My Active Listings
to bring up the Donation Manager.

Donation Manager