It is mostly "bought" and "brought." I know, that doesn't make it easier, so basically:

Acheter = to buy, it's a very common verb

J'ai acheté un ordinateur = I bought a computer

Amener = to bring (to somewhere)

J'ai amené mon ordinateur = I brought my computer (and it's here with me now)

Emmener = to bring (from somewhere)

J'ai emmené mon ordinateur = I brought my computer (and it's out there)

The distinction between amener and emmener is tenuous, but acheter is used in many cases to mean "to buy"

J'ai acheté une bouteille de vin ( I bought a bottle of wine) 

J'ai emmené une bouteille de vin ( I took a bottle of wine with me) which means I brought a bottle of wine. 

In hose two sentences "Acheter" and "Emmener" mean the same. 

Another example where those two verbs don t mean the same is: 

J'ai acheté un chien. (I bought a dog)

J'emmène mon chien balader. ( I m walking my dog)