Both items have a fixed price and quantity, but are available in different ways.
Buy Now Only items
These items can be listed on the auction webpage and are "for sale."
Buy Now Only items can only be selected (purchased) from the auction webpage.
Do not enter a Starting Bid or Bid Increment amount. Check Buy Now Only and enter the Buy Now Price and Quantity available.
Add-On items
These items are only available internally to DonorView users in Workspace > Auctions > Auctions.
In order to manually enter a bid on a fixed price item, the item should be set up as an Add-On.
An example of an add-on may be a paddle raise.
The add-on purchase can be entered as Pay Later, allowing all of the paddle raise bids to be entered first before processing payments.
On the Auction page Auction Settings step, Default To Pay Later For Addon Item(s) Purchases? can be set to YES to automatically have the field set when entering an Add-On purchase.