Get gold eagles and or Krugerrands and then get some of the other metals in coin form as well.
Also in many countries you can just go to a local bank and buy coins. Regardless of where you buy the coins make sure to ask them about their policy about buying coins with defects. Some small dealers may not pay full price if there are dents. Most big dealers don't seem to care about defects at all. Krugerrands tend to have more dings due to age but it is an allow so they are rare although there may be a tiny amount of wear from handling.
South African Gold Krugerrand 1 oz - Great National Pricing
American Gold Eagle 1 oz - Great National Pricing