While leveling, your character obtains skill points and AMPs points. The second ones can be used for unlocking AMPs. Tier 1 AMPs are unlocked by default, when you collect enough AMP points, but AMPS Tier 2 and Tier 3 are locked, and players have to unlock AMPs with corresponding AMP items first. AMPs items can be obtained as mob drops, quest rewards, or you can buy them from vendors.
In the table below you can find locations for all Esper Amps, for both factions Exile and Dominion. By clicking on the links in the Vendor columns you can see map location for each vendor. You can also search the table by choosing vendor name, or location from drop down menus at the top of the table.