After testing a few 125 KHz RFID tags from Amazon, I found these to be the best. (More in comments below) : r/flipperzero
Amazon Unveils RFID Technology for 'Shop and Go' Consumers
BMES EM18 125Khz RFID Reader Module + 5 x 125Khz RFID Tags : Amazon.in: Industrial & Scientific
Amazon.com : 100 pcs NFC Stickers NTAG215 Tag, Rewritable NFC Tags Round Labels 25mm (1 inch), 504 Bytes Memory Chip RFID Tag, Programmable for NFC-Enabled Devices and Nintendo Switch, Wii U &
Amazon.com : Hornady RFID Watch Band Tag - Universal RFID Tag Attaches to Your Watch Band, Opens Your RFID Safe - Keep Your Safe Key Accessible, Slips onto Your Watch Band -
Amazon.co.jp: UHF RFID Tags Seal Labels HEC Tread ALN-9874-WRW 100 Sheets : Office Products
Impinj Surges: Is Amazon Using Their RFID Tags? | Barron's
Amazon.co.jp: 10 Pack UHF RFID Tags Anti Interference Home Security : Industrial & Scientific
UHF RFID Tag: Amazon.de: Everything Else
Amazon.com : NFC NTAG213 Stickers/Tag/Adhesive Label RFID Tags with NTAG213 Chip 180 Bytes Fast Read/Write/Lock Compatible with All NFC-Enabled Smartphones and Devices (15PCS) : Office Products
Amazon.com : 20 Pieces MIFARE Classic 1K RFID Smart NFC Tags ISO14443A RFID Stickers 13.56MHz,Round Dia 25mm Adhesive NFC Tag by Timeskey NFC : Office Products
Amazon.com: KingGo 9662 Copperplate H3 70x17 UHF tag RFID Adhesive Tag Inlay RFID Label-100pcs : Everything Else
Robo India Rfid Tag Pair (Keychain+Card) : Amazon.in: Industrial & Scientific
rfid tag:Amazon.co.jp:Appstore for Android
Coin type 125KHZ RFID Card | EM RFID Tag Cards/size:25MM with Sticker 2PCS : Amazon.in: Industrial & Scientific
Amazon.co.jp: VKLSVAN 3pcs RFID Module FRC RC522 MFRC522 IC Card Reader Module + S50 Contactless IC Tag + Card Key Mifare : Industrial & Scientific