While most retail chains only sell full books of 20, some local pharmacies or independent convenience stores may sell individual stamps.
Yes, you can buy just in person, but your options for where to buy it are more limited than buying a full book. Where to Buy a Single Stamp can i buy just one stamp
Some The UPS Store locations are authorized USPS retailers and may sell single stamps, though they may charge a small convenience fee above the standard postage rate. Where You Likely Cannot Buy Just One THE UPS STORE - Newbury Park, California - Yelp While most retail chains only sell full books
This is the most reliable place to buy a single stamp. You can walk up to the window and purchase exactly one. you can buy just in person