Click "Collections" from the Catalog Manager.

Let's call this collection FloorLamps (Budget).

We're going set this collection to Immediately add/remove products so it will always be good to go.

We're going to set a rule that the custom field "Fixture Type" equals "Floor Lamp."

We're going to add another filter, "Price Less than $100."

Wait! The collection count could jump sky high. That's because it's currently including products that satisfy ANY of these conditions, and there are lots of products under $100. If we click on ALL, then it will only include products that match ALL the filter criteria.

We're now down to a nice manageable group of 121 Floor Lamps that we're going to do an Affordable Floor Lamp promotion around.