Local garden centers often have them in stock during the holiday season, or you can order them from specialized online bulb companies.
Avoid any bulbs that are soft, squishy, or have dark mold/rot spots. Scent Preferences: buy paperwhite bulbs
Here is a helpful review and buying guide for paperwhite bulbs, based on best practices and user experiences. Local garden centers often have them in stock
If you want continuous blooms from Thanksgiving to spring, buy large quantities and plan to plant them in stages. What to Look For (Buying Criteria) buy paperwhite bulbs