There are many ways to obtain Amber, though it may be a bit pricey.
Transmute Amber: You can convert Sunstones, Merle's Whiskers, Amber Dust, and Golden Pearls to Amber
Vendor: Buying it from the PVP vendor person (don't do PVP, sorry if I don't know his name) for Tickets. This is extremely expensive.
Boss Drops: Certain high level bosses, like Gladiator Dimachaerus or Hades are both sources of Amber.
Farming: Expensive in energy use. Certain plants drop Amber as a low chance. King Parsley, which has a chance of propagation (duplicating) is a good source.
Nabbing it from other characters on your account: This is always the case if you happen to have a character with unnecessary Amber accumulated that they don't need.
