YubiKey 4
$40.00
Yubico

If you're looking for a physical 2FA token to use with as many services as possible, this is it.

FIDO U2F Security Key
$17.99
Yubico

If you're not already riding the two factor authentication (2FA) bandwagon, this should be your ticket. The Yubico FIDO U2F Security Key is an ideal 2FA token because it doesn't require a battery or Internet connectivity. A must for securing sensitive accounts.